Parslow returned to fitness ahead of 2014–15, but having failed to regain his place in the team signed for Conference Premier club Grimsby Town on a one-month loan on 18 September 2014. He debuted two days later in their 1–0 away win over Kidderminster, and made seven appearances for Grimsby before the loan expired on 20 October 2014. Having been an unused substitute for three matches after returning to York, Parslow rejoined Grimsby on loan until 4 January 2015 on 7 November 2014, and made his second debut for the club a day later in a 3–1 home defeat to Oxford in the FA Cup first round. The loan was extended until the end of the season during January 2015. He came on as a 74th-minute substitute for Gregor Robertson in the 2015 Conference Premier play-off Final against Bristol Rovers at Wembley on 17 May 2015; following a 1–1 draw after extra time, Grimsby lost 5–3 in a penalty shoot-out. Parslow had made 23 appearances in his second loan spell at Grimsby, and after returning to York was released after nine years at the club.