Exhibit 32.1

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO SECTION 906 OF THE

SARBANES-OXLEY ACT OF 2002

The undersigned executive officers of Randolph Bancorp, Inc. (the “Company”) hereby certify that this Annual Report on Form 10-K for the year ended December 31, 2017 (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, and the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company as of and for the periods covered by the Report.

March 15, 2018	By:	/s/ James P. McDonough
		James P. McDonough
		President and Chief Executive Officer
		(Principal Executive Officer)
	By:	/s/ Michael K. Devlin
		Michael K. Devlin
		Executive Vice President and Chief Financial Officer
		(Principal Financial Officer)