Beginning his career at the age of 25, Crowley has released five albums, with his debut A Strange Kind arriving in 1999. He followed this with When You Are Here You Are Family (2002), A Northern Country (2004), Long Distance Swimmer (2007) and Season of the Sparks (2009). He has performed on TV shows such as Other Voices and Ceol Ar An Imeall and is also curator of the Homelights Festival in Dublin.
In a 2005 Rolling Stone interview, Ryan Adams cited Crowley when asked "Who's the best songwriter that no one's heard of". The Irish Times placed this artist at number eight in a list of "The 50 Best Irish Acts Right Now" published in April 2009.
Crowley has won the Choice Music Prize for Irish Album of the Year on one occasion for Season of the Sparks and been nominated on another occasion for Long Distance Swimmer. After winning the award for Irish Album of the Year 2009 he was among the first acts to be announced for Electric Picnic 2010.