Merrifield signed his first professional contract with AFC Wimbledon in December 2011, having joined the club's youth system at the age of 16 two years previously. Merrifield's contract with the club was extended on 18 May 2012. Merrifield made his league debut in a 5–1 defeat by Bradford City on 25 August 2012 as an 87th minute substitute for Christian Jolley. The midfielder scored his first senior goal for AFC Wimbledon in the First Round of the 2012-13 Football League Trophy on 4 September 2012. Despite a hotly contested derby the game ended as a 2–1 defeat by Southend United after Ryan Cresswell scored for the Shrimpers in the fourth minute of stoppage time. Merrifield made his first league start for the Dons on 8 September 2012 in a 2–0 defeat against Northampton Town. On 30 November 2012, Merrifield was loaned out to Isthmian League Premier Division side Harrow Borough on an initial two-month loan deal along with teammate Emmanuel Akokhia. He made his debut for The Boro in a 0–0 draw with Whitehawk on 1 December 2012. On 8 December 2012, he struck a first-half equaliser for Harrow Borough against East Thurrock United, with the match eventually ending as a 3–2 defeat. On 29 January 2013, Merrifield scored his second league goal in a 3–2 loss to Metropolitan Police. On 4 February 2013, it was announced that Merrifield's loan spell had been extended by a further month. On 4 March 2013, it was announced that Merrifield had returned to AFC Wimbledon having made seven appearances in total for Harrow Borough. On 1 July 2013, it was announced that Merrifield had left the club.
Hayes & Yeading United
Merrifield featured in two of Hayes & Yeading United's pre-season matches after Phil Babb made his interest in the midfielder known. On 27 July 2013, he scored one goal in the 3–1 victory over Wealdstone, in the 63rd minute. On 15 August, he was announced as one of the club's new summer signings.
On 31 May 2016, Merrifield joined manager Rod Stringer and teammate Anthony Church in the switch from Bishop's Stortford to Chelmsford City. On 30 December 2016, Chelmsford City confirmed on their official Twitter profile, that Merrifeld Canvey Island had joined on a dual registration.
