Started playing rugby at Deal & Betteshanger Rugby Club. Carley started refereeing at the age of 16, taking charge of Aylesford 3rds v Maidstone 4ths where he was obliged to give his first yellow card to the Maidstone prop, Rob Lindsay, following Lindsay punching a member of the opposite team. 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. In 2010, Carley was promoted to the National Panel of Referees where he started to referee at National 1 and 2 level and Championship.[2] That same year he debuted on the World Sevens Series in Dubai.
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.[3] On 4 May 2013, he officiated his first Premiership game, taking charge of London Welsh and Worcester Warriors. Carley later became the first referee to gain promotion from the Referee Academy into a full-time referee.[4]
He took charge of his first World Rugby appointed match, refereeing the United States against Russia in June 2016. In November 2016, he refereed his first Tier 1 nation, officiating Scotland's clash against Georgia. 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. He came under a lot of criticism for poor refereeing on the day; particularly for reacting too quickly and not allowing the game to play out properly. [7]