Born in Truro, he previously played in the Football League for Plymouth Argyle, having progressed through the club"s youth system. He later played for a single season at Truro City. Sims made his professional debut on 9 August 2011, in the Football League Cup 1–0 defeat to Millwall at Home Park.
This followed his appearance as an unused substitute in the 1–1 draw away at Shrewsbury the previous Saturday.
He signed a new undisclosed contract in April 2012, his first as a professional, along with team-mates Curtis Nelson and Luke Young. He ended his debut season in the first team with four appearances in all competitions.
Sims made two more appearances for Argyle before being released at the end of the 2012-2013 season. In June 2013, Sims signed for his home town club Truro City prior to their first season back in the Southern League.