Swift is currently nursing leg fracture but is expected to be back to full training in six to eight weeks.
Commenting on his decision to retire, he said:
"Whilst I've known this was coming for quite some time, it's still quite surreal to think I'll soon be saying goodbye to the team and the lads I've played with for so long. Connacht Rugby has been a huge part of my life for over 15 years and it's difficult to imagine no longer being involved. I've enjoyed every bit of my time with the province and have so many people to thank for the opportunities afforded to me.
"Professionally, I've been lucky to work with amazing coaches and back room staff throughout my time at Connacht and I'd like to pay particular tribute to Eric (Elwood), Dan (McFarland) and Tim (Allnutt) who have not only been my team mates and coaches down through the years but have also become good friends.
"I have no doubt that Connacht Rugby will continue to achieve great things in the years to come and I know I'll be shouting on the team with the rest of the supporters."
Connacht Assistant Coach, Dan McFarland, paid tribute to his former team mate:
"Michael and I worked together for 16 of the last 17 years and I cannot think of many players I have worked with who have shown as much honesty, endeavour and spirit. But not only would Swifty run through brick walls for his team mates, he has also been a great player, transforming himself from an athletic back rower to a hard hitting lock. I will miss working with him."
Willie Ruane, CEO Connacht Rugby said:
"I'm proud to say that I played and worked with Swifty. He has truly defied time and his contribution to Connacht Rugby will not be forgotten. I have no doubt that he will be as successful off the pitch as he has been on it and I wish him and Gill all the best for the future."
Head Coach Pat Lam added:
"It was clear from the very start of my time with Connacht Rugby that Swifty was at the core of what this province is about. His work ethic, passion and commitment to Connacht is inspirational to the management, players, sponsors and supporters.
"Swifty has always been a fantastic ambassador for this club and he will be greatly missed."
- Born in London in 1977, Swift played for Richmond Rugby Club as a flanker while in university, before spending a season at Leeds Tykes RFC.
- He joined Connacht in 2000 and earned his first cap for the province against Ulster that year whilst also playing for Galwegians RFC in the All Ireland League.
- December 2006, he earned his 100th cap for Connacht against Montpellier, becoming the fifth Connacht player ever to do so
- September 2011 he reached another milestone when he became the first Connacht player to reach 200 games
- 6'5" &123kg
- 13 appearances in the Heineken (now Champions) Cup
- 67 appearances in the Challenge Cup
- 183 appearances in the PRO12
- Total of 268 Connacht caps
- 'That try' against Leinster in the 2010 23-17 victory
- PRO12 Chairman's Award in 2013 in recognition of his outstanding service to both his province and the tournament as a whole.
- Launched two successful business ventures over the last five years whilst playing with Connacht Rugby.