The Munster wing is embarking on his first full season since his cross code switch in March when he came out of his two month retirement after quitting NRL side Gold Coast Titans.
Carney's actions earlier this year surprised many within the game as he announced he was leaving the Titans after not playing a game and only taking part in one training session.
"I have made this decision with a heavy heart and it has been a difficult decision for me to make," he said in a statement in January following his retirement.
"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.
"I know my mind is not up for this new challenge."
Carney then took on what many believe could be the biggest challenge of his professional life when, on March 15 at the age of 30, he signed for the then European champions on a two-year deal.
And it is quite possible that his form, and the speed with which he can adapt fully to union from league, could be absolutely key if Munster are to win back the Heineken Cup they surrendered to Wasps last season.
He played rugby union and gaelic football as a boy but made his name in league.
It was at Wigan where he was to become a star as he earnt international recognition by adding to caps for Ireland and then, in 2003, becoming the first Irishman to play for Great Britain since Tom McKinney in 1957.
That summer would prove to be his breakout season as he was included in the Super League 'Dream Team', the Rugby League World magazine World XIII and voted BBC North West's Rugby League Player of the Year.
In the summer of 2005 he agreed to join the Titans for the 2007 season after his Wigan contract expired in autumn 2006.
But, after finishing the season in England, he moved to Australia to join the Newcastle Knights for a single season before his change of heart and a return home.
And now back in Ireland he is set to build on what has been a fairly impressive start to his union career with both Munster and Ireland.
He scored tries in his first two matches for his new side and almost instantly earnt international recognition with a place in the Ireland squad to travel to Argentina.
A try on debut for his country in South America prompted Carney to be selected for the Irish World Cup squad with the praise of national coach Eddie O'Sullivan ringing in his ears.
O'Sullivan said: "I think Brian's adapted well. The question mark for him is making the transition from league to union. From what I've seen so far, he's doing that pretty seamlessly. He's a good professional.
"Probably the one thing in his favour is that he's played at a pretty high level. And he has been in the cauldron of international rugby, albeit in league rather than union. But he seems to have the temperament.
"And the question mark is can he make the transition to the next level up? I'm reasonably confident that he can, that's why I picked him and we'll have to see.
"But I think from what I've seen with Munster, he's acquitted himself very, very well. He's a very skilful player."
Despite being hailed by the national coach Carney did not play a single minute of rugby under him in Ireland's disastrous World Cup campaign and will be looking to prove his worth against the best the continent has to offer.