Midfielder Connolly joined Sligo Rovers in June 2012 and helped the club win their first Premier Division title in 35 years. He made a total of 17 appearances during his time at Sligo Rovers.
Connolly was loaned to Longford Town in July 2013 until the end of last season. He has also had spells with Derby County in England and Ayr United in Scotland.
Speaking on signing Connolly, manager Tommy Dunne said:
"We are very happy to sign Ryan. There was a bit of competition for him, but we got there in the end. It is a good statement for us because we want to attract players from the region to the club and getting somebody with Ryan’s quality shows what we are about. Ryan did reasonably well with Sligo Rovers when he came home from Derby. He mightn’t have got as much time as he would have liked in his preferred central midfield role. When he went on loan to Longford, though, he got the chance to play there more often and did very well."
Ryan Connolly is the ninth player to sign for Galway ahead of their debut season in the League of Ireland.
