In September 2004 he was first person to be offered a RFU refereeing scholarship at the University of Gloucestershire, which ran alongside his sports science degree.

[1] After graduating, he returned home and joined the RFU's South East Group of referees ahead of the 2008–09 season.

During the 2012–13 RFU Championship, Carley became the first ever referee in the world to officiate a professional game wearing "RefCam" when he took charge of the Newcastle Falcons and London Scottish.

During the 2017 Six Nations Championship, he made his first Six Nations appearance, acting as assistant referee to John Lacey during Scotland's game against Wales and subsequently has taken charge of his first Tier 1 International Test match at Murrayfield Stadium refereeing Scotland Vs New Zealand on 18 November 2017.

[6] In 2024 Carley was appointed as the referee for the Investec Champions Cup Final between Leinster Rugby and Stade Toulissant at the Tottenham Hotspur Stadium.