The midfielder has hung up his boots after a torrid time with knee problems.
Jack Collison joined West Ham United in 2005 as a 17-year-old and went on to play 113 games for the club, but it could have been much more.
Since dislocating his kneecap in March 2008 he has suffered with serious knee problems and never truly found his way back into regular first-team football.
He spent time at Ipswich Town, but never got fit and many have doubted the Welsh international's ability to get back in the game.
He returned to boyhood club Peterborough United last summer. He signed a one-year deal to join the League One club but his knee injuries have never truly healed.
Today he confirmed his retirement from the sport, aged just 27.
West Ham fans of course have fond memories of the midfielder, who also made 17 appearances for Wales, and will now look toward a future as a coach and in the football media.
He also spent time on loan at Bournemouth and Wigan Athletic during his professional career.
Since the announcement plenty of West Ham fans have been tweeting their best wishes to Collison after his retirement...
If reports are true, it's unlikely Jack Collison will feature in Mark Noble's testimonial next month as originally planned.— WHUFC_Daily (@WHUFC_Daily) February 12, 2016
really sad news about former Hammer Jack Collison retiring from football at just 27 with a chronic knee injury .step up @whufc_official— Danny Carr (@olympichammer) February 12, 2016
Sad news about Jack Collison ... decent player, and only 27. Seems a level headed chap.— Mike Flint from UK (@michaelfromuk) February 13, 2016
Collison retires aged 27— Gavin Brien (@gavbri10) February 13, 2016
Very sad news. This boy had bundles of potential but injury killed that. Good luck to himhttps://t.co/c0wJXePgny
Sad news as Jack Collison is forced to retire at the age of 27. Will always be welcome and loved at West Ham pic.twitter.com/ijBx7pRlKf— West Ham Transfers (@westhamtransfer) February 13, 2016
Sad to hear collison has retired, could've been a great— Boonie (@Joel_Boon) February 13, 2016
Sad to hear that Jack Collison has retired so young. A big player for us for a long time. Best of luck for the future.— D. S. North (@DS_North) February 13, 2016
Gutted for Jack Collison. We all knew this day was coming but such a shame for a great player and nice guy. Good luck to him in management.— Michael Walter (@MichaelWalter80) February 13, 2016