Career
Bristol City
Born in Bristol, Harley began his career with hometown club Bristol City. On 28 August 2004, Harley made his professional debut in a 3–0 loss against Portuguese Vale at Vale Park in League One. During the 2005-2006 season, Harley was loaned to then Conference National side Forest Green Rovers.
He made only 3 appearances for Rovers before returning to Bristol City.
Weston-super-Mare
In October 2006, Harley signed for Conference South side Weston-super-Mare. Exeter City
In November 2007, Harley signed for Conference side Exeter City.
He made his debut for the Grecians on 4 March 2008, coming on as a substitute for Andrew Taylor in a 2–2 draw against Crawley Town. The victory took the Grecians to the play-off final at Wembley where they were promoted back to the Football League.
On 16 January 2010, Harley scored both goals against Leeds United in a 2–0 victory at Saint James Park.
Harley scored the vital goal in the final game of the 2009-2010 season against Huddersfield Town. The victory ensured Exeter"s position in League One for the forthcoming season. Swansea City
On 21 January 2011, Harley signed for the then Championship side Swansea City on a free transfer.
He was loaned back to Exeter for the remainder of the 2010-2011 season.
In spite of the move, Harley would not make an appearance for the Swans. Swansea beat Reading in the Championship play-off final on 30 May 2011 to progress to the Premier League.
Brighton & Hove Albion
On 22 August 2011, Harley joined Championship side Brighton & Hove Albion on a 3-year deal for an undisclosed fee. Harley made his debut at home in a 1–0 victory against Sunderland in the League Cup.
In December 2012, Harley joined League One side MK Dons on loan for the remainder of the 2012-2013 season.
He made 11 appearances and scored 1 goal for the Dons. Swindon Town
Harley completed a free transfer to League One side Swindon Town on 26 July 2013 after his contract at Brighton was terminated. He made 25 appearances and scored 4 goals during the 2013-2014 season for the Robins.
Return to Exeter City
On 20 November 2014 Harley was loaned to his former club Exeter City until January.
He had previously trained with the club during the season. On 12 January 2015 Exeter signed Harley to an 18-month deal after his contract was cancelled by Swindon.