Thornton had trials with a number of Football League and Non League clubs and on 3 July 2012, he joined Welsh club Wrexham on trial with view to a permanent deal for the new season. After six months on trial Thornton signed for Wrexham on non-contract terms. Thornton made his debut in a 5–0 win in an FA Trophy match against Sutton United which Thornton scored the fifth goal in.
Thornton participated in trials with various Football League and Non-League clubs. On July 3, 2012, he joined Wrexham on trial for a permanent transfer. After six months of trial, Thornton signed with Wrexham under non-contract terms. He made his debut in a 5–0 win against Sutton United, scoring the fifth goal.