Arguably one of the best players under a high ball in Irish rugby, he was both an extremely strong defensive full-back and very threatening in attack.
Educated at Bangor Grammar School and Trinity College in Dublin, Cunningham was an all-round sportsman, playing tennis, squash and cricket at representative level before choosing a career in rugby.
He made his Ulster senior debut against Wasps in 1997 aged just 19, and was part of Ulster's European Cup winning squad of 1999 alongside his older brother Jan.
"Since the first game of the Magners League campaign last season, injury has dominated my time as a player," admitted Bryn, who turned 32 last March.
"Over the past 15 months I've worked incredibly hard and through considerable pain in order to regain full fitness but unfortunately it wasn't to be.
The Ireland 'A' international added: "Ulster Rugby has been a massive part of my life for the past 13 years. Ravenhill is like home, I love the place, the supporters, and everything about it.
"I will miss it dearly and wish everyone still involved in Ulster Rugby the success that they and the province deserve, success which I am sure, is just round the corner.
"I would like to take this opportunity to thank all the people involved over the years who have given me the opportunity to do something I love so much. I feel very privileged."
Commenting on Cunningham's decision, Ulster Rugby operations director David Humphreys commented: "Bryn has been a very popular member of our squad for a very long time and the news that he has decided to retire marks a sad day for Ulster Rugby.
"However, I've watched him closely over the past number of months as he has endeavoured to recover from his injuries and while he's endured the inevitable frustration with his usual good grace and humour, now his decision is made, I've no doubt that he will embrace life, post-rugby, with vigour and will relish the fresh challenges that lie ahead.
"The consummate professional, both on and off the pitch, there is little doubt that Bryn will be much missed at Ulster Rugby and I'd like to take this opportunity to wish him and his family the very best of luck for their future."