The 31-year-old was at Turner's Cross from 2002 to 2008, winning the League of Ireland title in 2005 and the FAI Cup in 2007 before joining Barnet. After three years with the Bees, O'Flynn moved to Exeter City scoring 25 goals in 133 appearances at St James Park.
A former Republic of Ireland Under-21 international, O'Flynn announced his happiness at returning to Cork City. "I’m delighted to be back, it’s like the good old days," O'Flynn told the club's official website. "The lads are flying and there is a good buzz around the place.
"I went to the Limerick game the other night, and you could see the buzz is back. The lads played some great football and they ran out comfortable winners. They play good attacking football and I am looking forward to being a part of that."
Cork have already added Cillian Morrison to their squad during the transfer window, and manager John Caulfield believes that O'Flynn adds more much-needed experience up front. "It’s brilliant to bring John in," Caulfield said.
"Obviously we know him well from his last spell at the club, where he won a league title and an FAI Cup. He’s been in England for the last six years and about a month ago he expressed an interest in coming back.”
"He has a wealth of experience which our younger players can learn from, but crucially for us he gives us more options up front which is what we need."