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SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16

of the Securities Exchange Act of 1934

For the month of May, 2017

Commission File Number: 001-09531

Telefónica, S.A.

(Translation of registrant’s name into English)

Distrito Telefónica, Ronda de la Comunicación s/n,

28050 Madrid, Spain

3491-482 87 00

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form 20-F  ☒            Form 40-F  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):

Yes  ☐            No  ☒

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):

Yes  ☐            No  ☒

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934:

Yes  ☐            No  ☒

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): N/A

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Telefónica, S.A.

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TELEFÓNICA, S.A.

Ordinary General Shareholders’ Meeting

By resolution of the Board of Directors of TELEFÓNICA, S.A., the shareholders are hereby called to the Ordinary General Shareholders’ Meeting, to be held in Madrid, at the Recintos Feriales of IFEMA (Feria de Madrid), Campo de las Naciones, Parque Ferial Juan Carlos I, Pabellón 3, at 12:00 p.m. on June 9, 2017 on second call, in the event that the legally required quorum is not reached and therefore the Meeting cannot be held on the first call that is hereby called on June 8, 2017 at the same place and time, in order to deliberate and decide upon the matters included in the following

AGENDA

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SUPPLEMENT TO THE CALL TO THE GENERAL SHAREHOLDERS’ MEETING

Shareholders representing at least three percent of the share capital may request the publication of a supplement to this call to the General Shareholders’ Meeting, including one or more items on the Agenda, provided the request is accompanied by the rationale therefor or, if appropriate, by a well-founded proposed resolution. This right must be exercised by means of verifiable notice (which will include the corresponding documents evidencing shareholder status) that must be received at the Company’s registered office (Gran Vía, número 28, Madrid, código postal 28013, to the attention of the General Secretary and Secretary of the Board of Directors) within five days of the publication of this call to meeting. In addition, and as provided in Section 519 of the Companies Act, shareholders representing at least three percent of the share capital may, within five days following publication of this notice of call, submit well-founded proposed resolutions on matters that have already been included or that must be included in the Agenda.

RIGHT TO RECEIVE INFORMATION

In connection with Items I, II, III, VI, and VIII on the Agenda, and pursuant to applicable laws and regulations, it is stated for the record that shareholders have the right to examine and obtain at the Company’s registered office, or to request the Company to send them, immediately and free of charge, a copy of the following documents:

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Pursuant to Sections 197 and 520 of the Companies Act, the shareholders may, until the fifth day prior to the date on which the General Shareholders’ Meeting is scheduled to be held and by completing the form posted on the Company’s corporate website (www.telefonica.com) for such purpose, or by postal correspondence sent to the Company’s registered office (Gran Vía, número 28, Madrid, postal code 28013, to the attention of the Office of the Shareholder (Oficina del Accionista), request such information or clarifications as they deem necessary, or ask such questions as they deem appropriate, regarding the matters included on the Agenda or about the information available to the public that has been provided by Telefónica, S.A. to the National Securities Market Commission (Comisión Nacional del Mercado de Valores) since May 12, 2016, i.e., the date on which the last General Shareholders’ Meeting was held, or regarding the Auditor’s reports mentioned above.

Independently of the right to receive information referred to above, as from the date of publication of the notice of call to meeting, the following documents and information, among others, may be viewed on the Company’s corporate website (www.telefonica.com) and in the WebApp (http://telefonica.com/meeting) if accessing though mobile devices:

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RIGHT TO ATTEND THE MEETING IN PERSON OR BY PROXY

The right to attend the General Shareholders’ Meeting hereby called accrues to shareholders that hold at least 300 shares registered in their name in the corresponding book-entry registry five days in advance of the date on which the Meeting is to be held and who provide evidence thereof by means of the appropriate attendance card or by producing a certificate issued by the Company or by any of the depositaries participating in Sociedad de Gestión de los Sistemas de Registro, Compensación y Liquidación de Valores, S.A.U. (IBERCLEAR), or by any other means allowed under applicable law.

Any shareholder having the right to attend the General Shareholders’ Meeting may be represented thereat by another person, who need not be a shareholder. A proxy may be granted by using the proxy-granting form printed on the attendance card or by any other means allowed by Law. The documents containing proxies for the General Shareholders’ Meeting must set forth the instructions regarding the direction of the vote. Where no express instructions are given, it shall be understood that the proxy-holder must vote in favor of the proposed resolutions submitted by the Board of Directors regarding the matters on the Agenda, and against the resolution in question in relation to any matters that are not included in the Agenda and are thus unknown on the date that the proxy is granted but which may be submitted to a vote at the General Shareholders’ Meeting.

If the proxy-granting document does not set forth a specific person to whom the shareholder grants the proxy, such proxy shall be deemed granted in favor of the Chairman of the Board of Directors of the Company or of such other person as may replace him as Chairman of the General Shareholders’ Meeting. In the event that the appointed representative is involved in a conflict of interest upon voting on any of the proposals, whether or not included in the Agenda, that are submitted to the shareholders at the General Shareholders’ Meeting, and the shareholder has not given specific voting instructions, the proxy shall be deemed granted to the Secretary for the General Shareholders’ Meeting.

Shareholders who do not hold the minimum number of shares required to attend may grant a written proxy in respect thereof in favor of another shareholder having the right to attend, or come together with other shareholders that are in the same situation, such that they reach the required number of shares, and grant a written proxy to one of such shareholders.

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PROXY-GRANTING AND VOTING BY MEANS OF LONG-DISTANCE COMMUNICATION

Pursuant to Articles 20 and 25 of the By-Laws and 13 and 22 of the Regulations for the General Shareholders’ Meeting and to the resolution adopted by the Board of Directors as permitted by the aforementioned provisions, the exercise of proxy representation and voting rights by means of long-distance communication shall be governed by the following provisions:

1.- Proxy-granting or voting prior to the General Shareholders’ Meeting by electronic means.

Shareholders wishing to grant a proxy or to cast their vote by electronic means prior to the holding of the General Shareholders’ Meeting must access the “2017 General Shareholders’ Meeting/Proxy-granting and Voting by Electronic Means” section available on the Company’s corporate website (www.telefonica.com) (the “Website”) and follow the instructions to grant a proxy or to exercise their right to vote prior to the General Shareholders’ Meeting that are specified therein.

To such end, shareholders must provide evidence of their identity on the software provided for such purpose on the above-mentioned Website by means of: (i) the Electronic National Identity Document, or (ii) a recognized, valid and current electronic user certificate, as provided in Electronic Signature Act 59/2003, of December 19, issued by the Spanish Public Certification Body (CERES), a division of the Fábrica Nacional de Moneda y Timbre (Spanish Royal Mint). The Company reserves the right to request such additional means of identification from shareholders as it deems necessary to verify their status as shareholders and to guarantee the authenticity of the vote and of the proxy-granting.

2.- Proxy-granting or voting prior to the General Shareholders’ Meeting by postal correspondence.

Shareholders wishing to grant a proxy or to cast their vote by postal correspondence may complete and sign the proxy-granting or distance voting card prepared by the Company and send it to the attention of the Office of the Shareholder (Distrito Telefónica, Ronda de la Comunicación s/n, Edificio Central, planta 2, 28050 Madrid).

Also, the shareholder may grant a proxy or vote through cards issued by depositories. In this case, the shareholder must complete the items relating to the proxy-granting or distance voting, if any, in the card issued by the depositary, and send it by postal correspondence to the Company, to the attention of the Office of the Shareholder (Distrito Telefónica, Ronda de la Comunicación s/n, Edificio Central, planta 2, 28050 Madrid).

Shareholders that are legal entities must send to the Company a photocopy of a power of attorney with sufficient powers, evidencing the authority of the individual signing the proxy-granting or distance voting card in the name of the legal entity.

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If a proxy is granted to a person other than one of the members of the Board of Directors, a copy of the proxy-granting card must be sent to the proxy-holder for delivery at the entry doors to the premises on the day of the General Shareholders’ Meeting.

Should they wish to revoke the proxy granted, shareholders must contact the Company, at the Office of the Shareholder (phone no.: 900 111 004) before midnight on June 5, 2017.

Shareholders may obtain the Company’s proxy-granting or distance voting card by downloading and printing it from the Website, by picking it up at the registered office of the Company, or by requesting the Office of the Shareholder (telephone 900 111 004 / mail [email protected]) to send them without charge.

3.- Provisions common to the exercise of proxy-granting or voting rights by means of long-distance communication.

In order to be valid, both the proxies granted and the votes cast prior to the General Shareholders’ Meeting by means of long-distance communication (whether by electronic means or by postal correspondence) must be received by the Company before midnight on June 5, 2017.

The proxy or distance vote shall only be deemed to be valid if the status as shareholder is confirmed, through verification of the fact that the ownership information and the number of shares provided by each person granting a proxy or voting by means of long-distance communication are the same as the data provided by IBERCLEAR. In the event of a discrepancy between the number of shares reported by the shareholder and the number set forth in the IBERCLEAR file, the number of shares provided by IBERCLEAR shall prevail for purposes of quorum and voting.

In the event of co-ownership of shares, the person granting the proxy or the vote from a distance shall be deemed to have been appointed to exercise the shareholder rights, if such person is one of the co-owners.

Attendance at the General Shareholders’ Meeting by a shareholder who has previously granted a proxy or voted by means of long-distance communication (whether by electronic means or by postal correspondence), shall render the proxy or the vote null and void.

In the event that a shareholder grants several proxies or casts several votes (whether by electronic means or by postal correspondence), the action (proxy-granting or voting) taken last shall prevail. If the time when the shareholder granted any of the proxies or cast any of the votes is uncertain, the vote (regardless of the means used to cast it) shall prevail over the proxy-granting. If the shareholder cast several votes in different directions, by electronic or postal means, the vote cast last shall prevail.

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The Company reserves the right to modify, suspend, cancel or limit electronic voting or proxy-granting mechanisms whenever technical or security reasons require it or make it advisable. If any of such instances occurs, it will be announced on the Company’s corporate website. All of the foregoing is without prejudice to the validity of the votes already cast and the proxies already granted and to shareholders’ attendance and proxy representation rights.

The Company shall not be liable for any damage that may be sustained by shareholders as a result of failures, overloads, downtime, failed connections or any other contingency of the same or like nature beyond the Company’s control that prevents the use of electronic voting or proxy-granting mechanisms. Accordingly, such circumstances shall not constitute an unlawful deprivation of shareholders’ rights.

Both proxies granted and votes cast by means of long-distance communication shall be rendered void by the disposal of the shares that the Company becomes aware of.

ELECTRONIC SHAREHOLDERS’ FORUM

Pursuant to the provisions of Section 539.2 of the Companies Act, on the occasion of the call to meeting and until the General Shareholders’ Meeting is held, Telefónica, S.A. has enabled an Electronic Shareholders’ Forum on the Company’s corporate website (www.telefonica.com), which shall be accessible, with appropriate safeguards, by both individual shareholders and any shareholder associations they may create.

Proposed resolutions sought to be submitted as a supplement to the agenda announced in the call to meeting may be published in the Forum, together with requests for adherence to such proposals, initiatives to reach the percentage sufficient to exercise a minority right provided by law, and proxy offers or solicitations.

The Forum is not a mechanism for online electronic conversation between the shareholders of Telefónica, S.A. and the voluntary associations they may create or a forum for electronic debate. The Forum is also not a channel for communication between Telefónica, S.A. and its shareholders and the associations they may create. The Forum is provided for the sole purpose of facilitating communications between Telefónica, S.A. shareholders and the voluntary associations they may create, on the occasion of the call to meeting and until the day the General Shareholders’ Meeting is held.

Instructions for access to and use of the Forum may be found in the “2017 General Shareholders’ Meeting/Electronic Shareholders’ Forum” section.

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PARTICIPATION OF A NOTARY AT THE MEETING

The Board of Directors has resolved to request the presence of a Notary Public to draw up the minutes of the General Shareholders’ Meeting, pursuant to Section 203 of the Companies Act, read together with Sections 101 and 103 of the Regulations of the Commercial Registry.

DATA PROTECTION

The personal data sent by the shareholders to the Company to exercise their rights to attend, grant proxies and vote at the General Shareholders’ Meeting, or the personal data provided for such purpose by the entities that are the depositaries of the shares held by such shareholders, shall be used by Telefónica, S.A. to manage the development, compliance with and control of the shareholding relationship. Such data shall be provided to the Notary Public exclusively in connection with the preparation of the notarized minutes of the General Shareholders’ Meeting.

Furthermore, pursuant to the Personal Data Protection Act, Organic Law 15/1999, of December 13, the data received will be kept in a file for which Telefónica, S.A. is responsible, and the purpose of which is to send shareholders information relating to their investment inherent to their status as shareholders of the Company, and the development, management and control of the exercise of their rights as shareholders, along with facilitating communication between shareholders on occasion of the General Shareholders’ Meeting. Shareholders may object to such processing at any time (for which purposes they may call the toll-free number 900 111 004).

The rights of access, correction, cancellation and challenge may be exercised by the owner of the personal data, who must provide evidence of the owner’s identity, by letter addressed to the Office of the Shareholder of Telefónica, S.A., Distrito Telefónica, Ronda de la Comunicación s/n, Edificio Central, planta 2, 28050 Madrid.

If the shareholder includes personal data of other individuals on the proxy-granting or distance voting card, the shareholder must advise them of the details set forth in the preceding paragraphs and comply with any other requirements that may apply for the proper communication of the personal data to the Company, without the Company having to take any other additional action in terms of information or consent.

Shareholders (and their proxies, if any) must use any personal data of any individual that the Company may have made available to them on the occasion of the exercise of their rights to receive information, to attend, to grant a proxy and to vote at the General Shareholders’ Meeting only in order to exercise such rights.

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FOR ANY ADDITIONAL INFORMATION, SHAREHOLDERS MAY CONTACT TELEFÓNICA’S SHAREHOLDERS OFFICE BY CALLING TOLL-FREE AT 900 111 004, FROM 9:00 A.M. TO 7:00 P.M., MONDAY THROUGH FRIDAY OR BY SENDING AN EMAIL TO [email protected].

Madrid, May 4, 2017

General Secretary and Secretary of the Board

2017 General Shareholders’ Meeting of

Telefónica, S.A.

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Telefónica, S.A.

ORDINARY GENERAL SHAREHOLDERS’ MEETING

OF TELEFÓNICA S.A. - 2017 -

PROPOSED RESOLUTIONS SUBMITTED BY THE BOARD OF DIRECTORS TO THE SHAREHOLDERS FOR DECISION AT THE GENERAL SHAREHOLDERS’ MEETING

June 8-9, 2017

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Telefónica, S.A.

Proposal regarding Item I on the Agenda: Results and management of the Board of Directors of Telefónica, S.A. during fiscal year 2016.

To approve the Individual Annual Accounts (Balance Sheet, Income Statement, Statement of Changes in Shareholders’ Equity, Cash Flow Statement and Notes), the Consolidated Financial Statements -Consolidated Annual Accounts- (Statement of Financial Condition, Income Statement, Global Income Statement, Statement of Changes in Shareholders’ Equity, Cash Flow Statement and Notes to the Consolidated Financial Statements), and the Management Reports of Telefónica, S.A. and its Consolidated Group of Companies for fiscal year 2016 (ended on December 31, 2016), as finalized by the Board of Directors at its meeting of February 22, 2017.

In the Individual Annual Accounts, the Balance Sheet as of December 31, 2016 discloses assets, liabilities and shareholders’ equity in the amount of 83,260 million euros each, and the Income Statement as of the end of the fiscal year shows a profit of 24 million euros.

In the Consolidated Financial Statements (Consolidated Annual Accounts), the Balance Sheet as of December 31, 2016 discloses assets, liabilities, and shareholders’ equity in the amount of 123,641 million euros each, and the Income Statement as of the end of the fiscal year shows a profit of 2,369 million euros.

To approve the corporate management of the Board of Directors of Telefónica, S.A. during fiscal year 2016.

*        *        *

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Telefónica, S.A.

Proposal regarding Item II on the Agenda: Approval of the Proposed Allocation of the Profits/Losses of Telefónica, S.A. for fiscal year 2016.

To approve the following Proposal for the Allocation of the Profits/Losses of Telefónica, S.A. for the fiscal year ended December 31, 2016:

To allocate the profits posted by Telefónica, S.A. in fiscal year 2016, in the amount of 24,330,134.27 euros, as follows:

*        *        *

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Telefónica, S.A.

Proposal regarding Item III on the Agenda: Re-election, ratification and appointment of Directors, if applicable.

In addition, a proposal will be made to the shareholders at the General Shareholders’ Meeting to ratify the interim appointments of Directors to fill vacancies, if any, made by the Board of Directors from the call to General Shareholders’ Meeting to the time immediately prior to the holding of the meeting.

*        *        *

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Telefónica, S.A.

Proposal regarding Item IV on the Agenda: Establishment of the number of members of the Board of Directors at seventeen.

In accordance with the provisions of article 29 of the Corporate Bylaws, to establish the number of members of the Board of Directors at seventeen, or at the relevant number pursuant to the resolutions adopted under item III on the agenda.

*        *        *

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Telefónica, S.A.

Proposal regarding Item V on the Agenda: Shareholder compensation. Distribution of dividends with a charge to unrestricted reserves.

To approve a distribution of cash dividends with a charge to unrestricted reserves through the payment during 2017 of the fixed amount of 0.40 euro, paid in two tranches, to each of the existing shares of Telefónica, S.A. entitled to participate in such distribution on the following dates of payment:

*        *        *

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Telefónica, S.A.

Proposal regarding Item VI on the Agenda: Delegation to the Board of Directors of the power to issue debentures, bonds, notes and other fixed-income securities and hybrid instruments, including preferred stock, in all cases be they simple, exchangeable, and/or convertible and/or granting the holders thereof a share in the earnings of the company, as well as warrants, with the power to exclude the pre-emptive rights of shareholders. Authorization to guarantee issuances by companies of the Group.

To delegate to the Board of Directors, in accordance with the general rules governing the issuance of debentures and pursuant to the provisions of sections 285, 297 and 511 of the Companies Act (Ley de Sociedades de Capital) and 319 of the Regulations of the Commercial Registry, (Reglamento del Registro Mercantil), and article 15 of the By-Laws, the power to issue, on one or more occasions, debentures, bonds, notes and other similar fixed-income securities or debt instruments (including warrants) or hybrid instruments (including, among others, preferred shares), that may be convertible into and/or exchangeable for shares, and/or giving the holders thereof a share in the earnings of the company, and to guarantee the issuance thereof, all in accordance with the following conditions:

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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The Board of Directors is further empowered, subject to receipt of the required authorizations and consents, to amend the repayment conditions of the securities, their term, interest rate and, in general, any of the conditions of the issuances made in reliance on this authorization.

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Notwithstanding the foregoing, limits on the minimum and/or maximum benchmark price of the shares may be established for purposes of the conversion and/or exchange thereof upon terms decided by the Board. In the event of an exchange for shares of another company (whether or not belonging to the Group), the same rules will apply, to the extent that they are appropriate and with such adjustments, if any, as may be necessary, provided, however, that such rules will refer to the listing price of the shares of such company on the respective market.

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Telefónica, S.A.

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Telefónica, S.A.

It is expressly stated for the record that if application is subsequently made for delisting the securities issued pursuant to this delegation of powers, such delisting shall be effected in compliance with the same formalities as for the application for listing to the extent applicable, and in such case, the interests of the shareholders or debenture-holders opposing or not voting on the resolution shall be safeguarded in compliance with the requirements set out in the Companies Act and related provisions, all of the foregoing pursuant to the provisions of the Securities Market Act (Ley del Mercado de Valores) and the provisions in implementation thereof. It is also expressly stated that the Company submits to the rules now existing or that may hereafter be issued regarding the Stock Exchanges, especially regarding trading, maintenance of the listing and de-listing.

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Telefónica, S.A.

Proposal regarding Item VII on the Agenda: Delegation of powers to formalize, interpret, remedy and carry out the resolutions adopted by the shareholders at the General Shareholders’ Meeting.

To authorize, on a several basis, the Executive Chairman of the Board of Directors, the Secretary of the Board of Directors and the Vice Secretary of the Board of Directors, such that, without prejudice to any other delegations included in the foregoing resolutions and any powers of attorney to convert existing resolutions into public instruments, any of them may formalize and implement the foregoing resolutions, with the power for such purpose to execute the public or private documents that may be necessary or appropriate (including documents for purposes of interpretation, clarification, further development, supplementation, correction of errors and curing of defects) for the most correct performance thereof and for the registration thereof, to the extent required, with the Commercial Registry (Registro Mercantil) or any other public registry, as well as to deposit the accounts of the Company and its Group.

*        *        *

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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Telefónica, S.A.

Proposal regarding Item VIII on the Agenda: Consultative vote on the 2016 Annual Report on Directors’ Remuneration.

To approve, on a consultative basis, the Annual Report on Directors’ Remuneration for fiscal year 2016.

It is hereby stated for the record that the full text of such Report has been made available to the shareholders, along with the other documentation relating to this General Shareholders’ Meeting, since the date of the call to meeting.

*        *        *

Translation from Spanish for informational purposes only. In the event of a conflict, the Spanish version prevails.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.