<PAGE>

                                                                    EXHIBIT 31.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER PURSUANT TO SECURITIES EXCHANGE ACT
RULE 13a-15(e)/15d-15(e) AS ADOPTED PURSUANT TO SECTION 302 OF THE
SARBANES-OXLEY ACT OF 2002

I, Richard L. Marcantonio, certify that:

1.    I have reviewed this quarterly report on Form 10-Q of G&K Services, Inc.;

2.    Based on my knowledge, this report does not contain any untrue statement
      of a material fact or omit to state a material fact necessary to make the
      statements made, in light of the circumstances under which such statements
      were made, not misleading with respect to the period covered by this
      report;

3.    Based on my knowledge, the financial statements, and other financial
      information included in this report, fairly present in all material
      respects the financial condition, results of operations and cash flows of
      the registrant as of, and for, the periods presented in this report;

4.    G&K Services, Inc.'s other certifying officer and I are responsible for
      establishing and maintaining disclosure controls and procedures (as
      defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for G&K Services,
      Inc., and have:

            (a) designed such disclosure controls and procedures, or caused such
      disclosure controls and procedures to be designed under our supervision,
      to ensure that material information relating to G&K Services, Inc.,
      including its consolidated subsidiaries, is made known to us by others
      within those entities, particularly during the period in which this report
      is being prepared;

            (b) evaluated the effectiveness of G&K Services, Inc.'s disclosure
      controls and procedures and presented in this report our conclusions about
      the effectiveness of the disclosure controls and procedures, as of the end
      of the period covered by this report based on such evaluation; and

            (c) disclosed in this report any change in G&K Services, Inc.'s
      internal control over financial reporting that occurred during G&K
      Services, Inc.'s most recent fiscal quarter that has materially affected,
      or is reasonably likely to materially affect, G&K Services, Inc.'s
      internal control over financial reporting;

5.    G&K Services, Inc.'s other certifying officer and I have disclosed, based
      on our most recent evaluation of internal control over financial
      reporting, to G&K Services, Inc.'s auditors and the audit committee of G&K
      Services, Inc.'s board of directors (or persons performing the equivalent
      functions):

            (a) all significant deficiencies and material weaknesses in the
      design or operation of internal control over financial reporting which are
      reasonably likely to adversely affect G&K Services, Inc.'s ability to
      record, process, summarize and report financial information; and

            (b) any fraud, whether or not material, that involves management or
      other employees who have a significant role in G&K Services, Inc.'s
      internal control over financial reporting.

Date: May 6, 2005

                                    By: /s/ Richard L. Marcantonio
                                        ---------------------------------------
                                        Richard L. Marcantonio
                                        President and Chief Executive Officer
                                        (Principal Executive Officer)