His professional career kicked off in 1997 when he was drafted into the Munster squad under then-new coach Declan Kidney.
Due to his withdrawal John O'Neill started in his place[2] He was part of the Munster team that beat Neath to win the 2002–03 Celtic League, and he picked up more silverware when Munster beat Scarlets to win the Celtic Cup in May 2005.
[3] Horgan started for Munster as they beat Biarritz 23-19 to win their first Heineken Cup final in May 2006.
[5] Horgan was Munster's all-time leading try scorer, with 41 tries to his name when he retired in May 2009, until Simon Zebo broke that record in March 2016.
[7] Horgan was selected in Ireland's squad for the 2003 Rugby World Cup, but he did not feature in the tournament.