Bell, who has made over 200 appearances for Bath, will retire with five England caps to his name, his last appearance coming against New Zealand at Twickenham in 2009.
The 37-year-old made his Red Rose debut during the 2005 RBS 6 Nations against Italy at Twickenham and also represented Harlequins, Ebbw Vale, Sale Sharks and Pontypridd at club level.
Bell will now focus on his business interests - having trained as a mortgage and insurance adviser in his spare time - after calling time on his playing career.
"I have had a fantastic career, from starting out at Quins through to the last nine years here with Bath," he said.
"I began playing rugby for Bath Minis, so to have had such a long career here has been amazing and it's been an honour to run out in the Bath shirt over 200 times."
On declaring his intention to hang up his boots at the end of the season, Bell also spoke openly about his struggle with depression, with Rugby Players' Association CEO Damian Hopley praising the player's decision to speak out.
"On behalf of all of our RPA members I would like to commend and congratulate Duncan Bell, not only on his outstanding rugby career, but also on his extremely brave decision to address the issue of depression as he retires from the game in order to help his peers who may be facing similar challenges in their lives," Hopley said.
"To the outside world, Duncan has always appeared the most upbeat of characters, rarely without a smile on his face and always one to make or take a joke.
"Privately, Duncan has had some considerable challenges in his life and I cannot speak highly enough of the courage he is now showing to speak openly about the depression he has suffered from over the past few years."