Galwegians' second try, scored by Derek Boyd, was enough to tip the scales in their favour - two tries to one - and so the Glynn Cup has returned to Glenina for the first time since 1992.
Speaking afterwards, Connacht President Michael Grealish said: "I'm thrilled with the event and how well it has worked out. It's fantastic to see this competition taking place once again and the new format certainly worked well.
"I'm sure everyone involved is already looking forward to next year's competition which I hope will prove to be just as exciting.
"I'd like to compliment Eugene Doyle, President of Corinthians, and Mick Casserly, President of Galwegians, and the organising committees from both clubs for putting together this festival of rugby.
"I'd also like to congratulate Galwegians RFC on claiming the title for the first time in over a decade, it's been a long wait but a thoroughly deserved win.
"I'd also like to express my sincere thanks to the Glynn family for their involvement and I hope that now that this competition has been restarted, it will continue for many years to come."