UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 6-K

Report of Foreign Issuer

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

the Securities Exchange Act of 1934

Dated: December 13, 2016

Commission file number 001-15254

ENBRIDGE INC.

(Exact name of Registrant as specified in its charter)

200, 425 – 1^st Street S.W.

Calgary, Alberta, Canada T2P 3L8

(Address of principal executive offices and postal code)

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  ☑

THIS REPORT ON FORM 6-K SHALL BE DEEMED TO BE INCORPORATED BY REFERENCE IN THE REGISTRATION STATEMENTS ON FORM S-8 (FILE NO. 333-145236, 333-127265, 333-13456, 333-97305 AND 333-6436), FORM F-3 (FILE NO. 333-185591), FORM F-4 (FILE NO. 333-213764) AND FORM F-10 (FILE NO. 333-213234) OF ENBRIDGE INC. AND TO BE PART THEREOF FROM THE DATE ON WHICH THIS REPORT IS FURNISHED, TO THE EXTENT NOT SUPERSEDED BY DOCUMENTS OR REPORTS SUBSEQUENTLY FILED OR FURNISHED.

On December 13, 2016, Enbridge Inc. (the “Company” or “Enbridge”) announced that it has entered into a timing agreement with the United States Federal Trade Commission (the “FTC”) pursuant to which the Company has agreed (i) not to consummate the proposed combination of the Company and Spectra Energy Corp (“Spectra Energy”) prior to 45 days after both the Company and Spectra Energy have substantially complied with the FTC’s November 2, 2016 request for additional information and documentary material relating to such transaction (the “Second Request”), unless the Company and Spectra Energy have received written prior notice that the FTC has closed its investigation, and (ii) not to certify compliance with the Second Request before January 10, 2017. Spectra Energy also entered into a timing agreement with the FTC on the same terms. The Company and Spectra Energy are continuing to work closely and cooperatively with the FTC in its review of the proposed combination.

FORWARD-LOOKING INFORMATION

This communication includes certain forward looking statements and information (“FLI”) to provide Enbridge and Spectra Energy’s shareholders and potential investors with information about Enbridge, Spectra Energy and their respective subsidiaries and affiliates, including each company’s management’s respective assessment of Enbridge, Spectra Energy and their respective subsidiaries’ future plans and operations, which FLI may not be appropriate for other purposes. FLI is typically identified by words such as “anticipate”, “expect”, “project”, “estimate”, “forecast”, “plan”, “intend”, “target”, “believe”, “likely” and similar words suggesting future outcomes or statements regarding an outlook. All statements other than statements of historical fact may be FLI. In particular, this document contains FLI pertaining to, but not limited to, information with respect to the proposed transaction jointly announced by Enbridge and Spectra Energy on September 6, 2016.

Although we believe that the FLI is reasonable based on the information available today and processes used to prepare it, such statements are not guarantees of future performance and you are cautioned against placing undue reliance on FLI. By its nature, FLI involves a variety of assumptions, which are based upon factors that may be difficult to predict and that may involve known and unknown risks and uncertainties and other factors which may cause actual results, levels of activity and achievements to differ materially from those expressed or implied by these FLI, including, but not limited to, the following: the timing and completion of the transaction, including receipt of regulatory and shareholder approvals and the satisfaction of other conditions precedent; interloper risk; the realization of anticipated benefits and synergies of the transaction and the timing thereof; the success of integration plans; the focus of management time and attention on the transaction and other disruptions arising from the transaction; estimated future dividends; financial strength and flexibility; debt and equity market conditions, including the ability to access capital markets on favorable terms or at all; cost of debt and equity capital; potential changes in the Enbridge share price which may negatively impact the value of consideration offered to Spectra Energy shareholders; expected supply and demand for crude oil, natural gas, natural gas liquids and renewable energy; prices of crude oil, natural gas, natural gas liquids and renewable

2

energy; economic and competitive conditions; expected exchange rates; inflation; interest rates; tax rates and changes; completion of growth projects; anticipated in-service dates; capital project funding; success of hedging activities; the ability of management of Enbridge, its subsidiaries and affiliates to execute key priorities, including those in connection with the transaction; availability and price of labor and construction materials; operational performance and reliability; customer, shareholder, regulatory and other stakeholder approvals and support; regulatory and legislative decisions and actions; public opinion; and weather. We caution that the foregoing list of factors is not exhaustive. Additional information about these and other assumptions, risks and uncertainties can be found in applicable filings with Canadian and U.S. securities regulators, including any proxy statement, prospectus or registration statement to be filed in connection with the transaction. Due to the interdependencies and correlation of these factors, as well as other factors, the impact of any one assumption, risk or uncertainty on FLI cannot be determined with certainty.

Except to the extent required by law, we assume no obligation to publicly update or revise any FLI, whether as a result of new information, future events or otherwise. All FLI in this document is expressly qualified in its entirety by these cautionary statements.

ADDITIONAL INFORMATION AND WHERE TO FIND IT

Enbridge has filed with the U.S. Securities and Exchange Commission (the “SEC”) a registration statement on Form F-4, which was declared effective by the SEC on November 14, 2016, which includes a proxy statement of Spectra Energy that also constitutes a prospectus of Enbridge, as well as other documents in connection with the merger of Enbridge and Spectra Energy (the “Transaction”). The definitive proxy statement/prospectus has been sent to the shareholders of Spectra Energy. INVESTORS AND SHAREHOLDERS OF SPECTRA ENERGY ARE URGED TO READ THE REGISTRATION STATEMENT AND THE DEFINITIVE PROXY STATEMENT/PROSPECTUS, AND ANY OTHER DOCUMENTS FILED OR TO BE FILED WITH THE SEC IN CONNECTION WITH THE TRANSACTION WHEN THEY BECOME AVAILABLE, AS THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT ENBRIDGE, SPECTRA ENERGY, THE TRANSACTION AND RELATED MATTERS. The registration statement and the definitive proxy statement/prospectus are available, and other documents filed by Enbridge and Spectra Energy with the SEC, when filed, will be available, free of charge at the SEC’s website at www.sec.gov. In addition, investors and shareholders can obtain free copies of the definitive proxy statement/prospectus, and will be able to obtain other documents which will be filed with the SEC by Enbridge, on Enbridge’s website at www.enbridge.com or upon written request to Enbridge’s Investor Relations department, 200, 425 First St. SW, Calgary, AB T2P 3L8 or by calling 1-800-481-2804 within North America and 1-403-231-5957 from outside North America, and can obtain free copies of the definitive proxy statement/prospectus, and will be able to obtain other documents filed with the SEC by Spectra Energy, upon written request to Spectra Energy, Investor Relations, 5400 Westheimer Court, Houston, TX 77056 or by calling 1-713-627-4610. You may also read and copy any reports, statements and other information filed by Spectra Energy and Enbridge with the SEC at the SEC public reference room at 100 F Street N.E.,

3

Room 1580, Washington, D.C. 20549. Please call the SEC at 1-800-732-0330 or visit the SEC’s website for further information on its public reference room. This communication shall not constitute an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to appropriate registration or qualification under the securities laws of such jurisdiction. No offering of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the U.S. Securities Act of 1933, as amended.

PARTICIPANTS IN THE SOLICITATION OF PROXIES

This communication is not a solicitation of proxies in connection with the Transaction. However, Enbridge, Spectra Energy, certain of their respective directors and executive officers and certain other members of management and employees, under SEC rules, may be deemed to be participants in the solicitation of proxies in connection with the Transaction. Information about Enbridge’s directors and executive officers may be found in its Management Information Circular dated March 8, 2016 available on its website at www.enbridge.com and at www.sedar.com. Information about Spectra Energy’s directors, executive officers and other members of management and employees may be found in its 2015 Annual Report on Form 10-K filed with the SEC on February 25, 2016, and definitive proxy statement relating to its 2016 Annual Meeting of Shareholders filed with the SEC on March 16, 2016. These documents can be obtained free of charge from the sources indicated above. Additional information regarding the interests of such potential participants in the solicitation of proxies in connection with the Transaction is included in the definitive proxy statement/prospectus, and will be included in other relevant materials filed with the SEC when they become available.

4

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.