Carney explained on the club’s official website the reasons for his decision, saying he felt he could not see the season out and would be letting down the club as a whole by carrying on.
"I have made this decision with a heavy heart and it has been a difficult decision for me to make," he said.
"But I dearly want to get home to my family and I couldn't act like a fraud by taking the club's money when I knew in my heart I couldn't see the year out.
"The boys are a great bunch of lads and I could not do it to them. Continuing on would have been for all the wrong reasons and I have never played the game for money.
"It has been for the challenge and I know my mind is not up for this new challenge."
Carney began his professional rugby league career with Gateshead, having started out as a Gaelic Footballer in his native Ireland.
From there he moved to Hull and then on to Wigan, where he scored 42 tries in 101 appearances for the club and earned his place in the Great Britain & Ireland side.
It was with the Lions that Carney shone on the international stage, and he was given a contract to join Gold Coast in 2007, and spent 2006 with Newcastle Knights where he was voted the competitions best winger.
"To ensure there is no speculation about my future I have told the Titans to hold back a contractual release so that offer may go some way to ensure that media speculation is not about me doing this to go back to Great Britain to play rugby league or rugby union," he added.
"I have made this decision to return home so I can go back to the UK to finish my Masters and to reunite with my family. I have always made decisions for me and now it is time for me to make a decision that is in the interests of my family."