Bealham earned a contract with the Connacht Academy following his performances with the Ireland U20's in the 2011 Six Nations and Junior World Championship. He made his PRO12 debut when he came on from the bench away to Zebre in February 2014.
The Australian-born, former rugby league player, whose grandmother is from Enniskillen, Co. Fermanagh, graduated to a senior contract under Pat Lam ahead of the 2014/15 season and has since racked up 57 appearances. Last season, Bealham, who can play on both sides of the scrum, was the only player to feature for Connacht in all 31 games across the Guinness PRO12 and European Challenge Cup.
Commenting on the contract extension, Connacht CEO Willie Ruane said:
"We are delighted to announce that Finlay will continue to play his rugby with Connacht Rugby. Having come through the Academy system here, it's tremendous to have witnessed his development and rise to the international stage over the last number of years.
"Finlay is an important part of our vision going forward as an organisation. I have no doubt that he has an exciting future ahead of him with Ireland and it's fantastic that he will be representing Connacht at the same time."
Head Coach Pat Lam said:
"Finlay is coming off the back of a very successful season with both Ireland and Connacht and I'm very pleased for us and our supporters that he will be with us for the next three seasons. From day one, I've been impressed with Finlay's attitude and desire to continuously learn on and off the pitch. He is a real team man and extremely popular among our squad.
"As a young, versatile front row player, he has a lot to offer our team as we head into another challenging but exciting campaign in both the Guinness PRO12 and European Champions Cup."
Finlay added:
"It was a fairly straightforward decision for me to sign on with Connacht. This place has become home for me over the last five years and I'm loving my rugby here. It's been a great few years, with last season an obvious stand out. Pulling on the Ireland jersey in the same season as winning the Guinness PRO12 with my team mates will live long in the memory.
"I can't wait to get back into it now in a few weeks' time and I'm confident we can go on to achieve more and more as a team."