He has impressed at British & Irish Cup level and was the starting hooker in the 2010 British & Irish Cup final. He was also a member of the Munster 'A' squad that captured the British & Irish Cup title last season.
He earned his sixth cap for Munster during their 2013 opener earlier this month against the Cardiff Blues.
Speaking about the signing of the 25-year-old forward, Connacht Rugby CEO Tom Sears said: "We are delighted to have been able to bring Sean back to his home province and have no doubt he will bring real quality to our squad and increase the competition for a place at hooker.
"He was very highly regarded at Munster and it is great news that he sees his future with Connacht."