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EXHIBIT 99.5

CERTIFICATION

REQUIRED BY RULE 13a-14(b) OR RULE 15d-14(b) AND

SECTION 1350 OF CHAPTER 63 OF TITLE 18

OF THE UNITED STATES CODE

Gildan Activewear Inc. (the “Corporation”) is filing its annual report on Form 40-F for the fiscal year ended December 31, 2017 (the “Report”) with the United States Securities and Exchange Commission.

I, Glenn J. Chamandy, President and Chief Executive Officer of the Corporation, certify, pursuant to 18 U.S.C. section 1350, as enacted pursuant to section 906 of the Sarbanes-Oxley Act of 2002, that, to the best of my knowledge:

1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the U.S. Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Corporation.

Dated: February 23, 2018

/s/ Glenn J. Chamandy                      

Name:    Glenn J. Chamandy

Title:    President and Chief Executive Officer

CERTIFICATION

REQUIRED BY RULE 13a-14(b) OR RULE 15d-14(b) AND

SECTION 1350 OF CHAPTER 63 OF TITLE 18

OF THE UNITED STATES CODE

Gildan Activewear Inc. (the “Corporation”) is filing its annual report on Form 40-F for the fiscal year ended December 31, 2017 (the “Report”) with the United States Securities and Exchange Commission.

I, Rhodri J. Harries, Executive Vice-President, Chief Financial and Administrative Officer of the Corporation, certify, pursuant to 18 U.S.C. section 1350, as enacted pursuant to section 906 of the Sarbanes-Oxley Act of 2002, that, to the best of my knowledge:

1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the U.S. Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Corporation.

Dated: February 23, 2018

/s/ Rhodri J. Harries                        

Name:    Rhodri J. Harries

Title: Executive Vice-President, Chief Financial and Administrative Officer