Carney began his career with the Canberra Raiders, scoring two tries on his debut in a 34–16 win over the Brisbane Broncos in June 2008.[5][6]
He suffered a broken leg during a match against Gold Coast in July 2009, which ruled him out for the rest of the 2009 season and all the 2010 season.[7][8]
Carney was nominated for the 2009 Ken Stephen Medal, acknowledging his strong community work.[9]
Sydney Roosters
Carney joined Sydney Roosters in July 2010.[10] He spent two seasons at the club, scoring three tries in 17 games.[8]
Castleford Tigers
Carney joined Castleford Tigers on a two-year contract from the 2013 season.[8] Coach Ian Millward said of him, "Justin will become a crowd pleaser with his robust running and dynamic style. No one will run the ball harder or faster in the Super League in 2013."[8] Carney scored 31 tries in 28 games for Castleford and, in
April 2014, signed a new five-year deal up to the end of 2019.[11]
However, he was suspended by Castleford in August 2015 and did not play again for the rest of the season.[13][14] He had scored 63 tries in 62 games since joining Castleford in 2013.[14]
Salford Red Devils
Carney joined Salford Red Devils in November 2015 on a one-year loan deal,[14] which was converted to a permanent three-year deal in April 2016.[15] He received an eight-match ban in May 2017 after being found guilty of racial abuse and left Salford by mutual consent.[16][17]
Hull KR
After leaving Salford, Carney joined Hull Kingston Rovers for the rest of the 2018 season.[17] He retired at the end of the season and returned to Australia,[18][19] where he joined Nyngan Tigers as captain-coach for 2019.[20]
On 3 July 2023 it was reported that he had received a lengthy ban whilst playing for his new club Albury Thunder, where he is the player-coach.[21]