FORM 6-K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16

under the Securities Exchange Act of 1934

For the month of April, 2015

001-14832

(Commission File Number)

CELESTICA INC.

(Translation of registrant’s name into English)

844 Don Mills Road

Toronto, Ontario

Canada M3C 1V7

(416) 448-5800

(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:

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

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

Furnished Herewith (and incorporated by reference herein)

The information furnished in this Form 6-K is not incorporated by reference into any registration statement (or into any prospectus that forms a part thereof) filed by Celestica Inc. with the Securities and Exchange Commission.

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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.

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EXHIBIT INDEX

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Exhibit 99.1

Celestica Expands Business Relationship with Honeywell Aerospace

Agreement further strengthens Celestica’s aerospace and defense offering through acquisition of key capabilities

TORONTO, Canada - Celestica Inc. (NYSE, TSX: CLS), a global leader in the delivery of end-to-end product lifecycle solutions, today announced that Honeywell Aerospace has subcontracted to Celestica final assembly and test, and repair and overhaul (R&O) for certain product lines, including electric power, and air and thermal management systems at Honeywell’s facility in Mississauga, Ontario, Canada. The assembly and test operations continue to be based at the Mississauga location, but are now managed by Celestica.

As part of this agreement, approximately 330 full-time employees from the Honeywell Mississauga location have joined Celestica.

“This agreement further strengthens the relationship between Celestica and Honeywell Aerospace and provides the platform for Celestica to deliver additional value to Honeywell,” said Craig Muhlhauser, Chief Executive Officer, Celestica. “The operational and regulatory capabilities that Celestica has acquired as part of this agreement, combined with the skills and experience of the team in Mississauga, complement the broad range of aerospace and defense solutions we can offer our customers globally and further differentiates us in the marketplace.”

About Celestica

Celestica is dedicated to delivering end-to-end product lifecycle solutions to drive our customers’ success. Through our simplified global operations network and information technology platform, we are solid partners who deliver informed, flexible solutions that enable our customers to succeed in the markets they serve. Committed to providing a truly differentiated customer experience, our agile and adaptive employees share a proud history of demonstrated expertise and creativity that provides our customers with the ability to overcome complex challenges.

For further information about Celestica, visit our website at www.celestica.com. Our securities filings can also be accessed at www.sedar.com and www.sec.gov.

Cautionary Note Regarding Forward-Looking Statements

Statements contained in this press release which are not historical facts are forward-looking statements. Such forward-looking statements are predictive in nature and may be based on current expectations, forecasts or assumptions involving risks and uncertainties that could cause actual outcomes to differ materially from the forward-looking statements themselves.  Such forward-looking statements include, without limitation, statements regarding strengthened customer relationships, anticipated value creation, and market differentiation in our aerospace and defense offerings through the acquisition of new operational and regulatory capabilities, and may, without limitation, be preceded by, followed by, or include words such as “believes”, “expects”, “anticipates”, “estimates”, “intends”, “plans”, or similar expressions, or may employ such future or conditional verbs as “may”, “might”, “will”, “could”, “should”, or “would”, or may otherwise be indicated as forward-looking statements by grammatical construction, phrasing or context. For those statements, we claim the protection of

the safe harbor for forward-looking statements contained in the U.S. Private Securities Litigation Reform Act of 1995, and in applicable Canadian securities laws. Forward-looking statements are not guarantees of future actions, events or outcomes. You should understand that the risks, uncertainties and factors which are identified in our various public filings at www.sedar.com and www.sec.gov could affect our future actions, events and outcomes and could cause them to differ materially from those expressed in such forward-looking statements. Forward-looking statements are provided for the purpose of providing information about management’s current expectations and plans relating to the future. Readers are cautioned that such information may not be appropriate for other purposes. Except as specifically required by applicable law, we disclaim any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

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