On completing his studies Holley gained employment at CCTA (now Coleg Sir Gar) and signed as a fullback for Aberavon RFC until an injury sustained in a match in 1994 against South Africa which saw him forced to end his playing career at the age of 24.
Holley was appointed as assistant coach for the Wales national team's 2009 summer tour of North America, with responsibility for defence.
[4] The 2009–10 season saw Scott Johnson join the Ospreys as Director of Rugby, with Holley remaining at the region as head coach.
[8] Bristol gained promotion to the English Premiership under Holley's leadership at the end of the 2015/16 season beating Doncaster in their third play off final in as many years.
He is an Ambassador for the charity Rugby For Heroes as well as the Velindre Cancer Centre and works closely with sports travel company Venatour.