The 31-year-old front rower explained: "Michael Bradley flew me over, showed me what Connacht was about, what they wanted to achieve and I haven't looked back since.
"I knew Swifty (Michael Swift), who was already here, so I spoke to him and I had always had the ambition to play in Ireland.
"When Brads phoned it was a good time in my career to make the move and I'm delighted to get my 100th cap for Connacht."
Flavin amassed 84 caps whilst at London Irish and was part of the Ireland Under-19 squad that won the FIRA World Youth Championship in 1998.
He has played for Ireland in the Under-21 World Championship and won caps for Ireland 'A' against England Saxons and Scotland.
He recently signed a two-year contract extension that will see him stay at the Sportsground until 2013.
"I made my debut for Connacht against the Border Reivers in September 2006, a match which we won," he said.
"Brett Wilkinson, Michael Swift, Keith Matthews and John Muldoon were all part of that team. They've all reached 100 caps as well so it great to join that elite group within the squad.
"We've a great group of players here at the moment. There's a real buzz around the team and it's great to see some of the younger players coming through with the likes of Eoin Griffin, Shane Conneely and Eoin McKeon breaking through to the squad.
"I've played in some big games over the years, one of the highlights was captaining the side in our victory over Samoa earlier this season.
"It's games like that you really want to be part of and hopefully there'll be many more like that at the Sportsground.'
Flavin added: "Winning my 100th cap for Connacht is a proud achievement for me and my family. Having my wife and son there to watch it, and my parents watching on television means a huge amount to me.
"I've five good years behind me here and hopefully there'll be plenty more to come. I'm really enjoying my rugby at the moment and I'm not hanging up my boots yet!"