Flanagan was spotted by the Blues playing for Pontypridd
The Ospreys have signed fly-half Dai Flanagan on a three-year-contract from the Cardiff Blues.
Flanagan, 24, came through the Blues academy and made his debut in May 2006 in the 37-8 defeat at Munster.
He went on to make 25 appearances for the Blues scoring 41 points, but has found first-team action limited.
"I realise there are some excellent fly-half at the Ospreys, but I'm coming here to prove myself," said former Wales youth Flanagan.
"I wouldn't have signed if I thought that I'm just be going to make up the numbers and wouldn't get any game time.
"It's a long season, and with the international commitments that the Ospreys have then there's plenty of opportunities for me to show what I can do."