Colchester United's young midfielder / full back Sean Hillier spent some time with Norwich before joining Colchester's centre of excellence in 1996. Sean comes from Clacton and has progressed through the ranks at Layer Road to play in the Youths and Reserves, and has been called up to the bench for the first team. However his development did not continue and he was freed at the end of January 2001 along with Jack Wignall. Both players were in the final year of three year scholarships. [Source: Sport First, 4th February 2001]

The Non-League Magazine stated that in the summer of 2001, Sean joined Canvey Island who are expected to win the Ryman League Championship. However the Green Un of 18th August said Sean lined up for Dr Martens side Chelmsford City ! The Green Un was right but not for long as Sean was released by Chelmsford on 26th August

Sean then since signed for Clacton Town (his hometown team). Despite a bid from Braintree Town in July 2002, Sean has extended his contract with Clacton.

He made his debut (and only appearance) for Brentford in the Football League Trophy, in the 3–0 home defeat against Milton Keynes Dons on 28th September 2004. He then played one game for AFC Wimbledone

In October 2005, Sean signed a two year contract with Wivenhoe for whom his brother Paul had already signed. Sean returned to Clacton at the end of June 2006. He has played over 300 games for Clacton. He was named Assistant to manager Andy Taylor in July 2011

He works for the Chelsea FC Foundation