Alex Loudon, 27, has ended his cricket career just 16 months after playing for England in a one-day international.
Loudon celebrates a wicket in last summer's Twenty20 Cup
The all-rounder's departure will be a huge loss to his county Warwickshire, where Ashley Giles is beginning his stint as the director of cricket.
Loudon said: "I had been offered a contract for next season, but have decided that the time is now right for me to begin a new career in business."
Giles added: "Alex has always had a good mix of outside interests."
Loudon was selected for England's Test squad for the 2005-06 tour to Pakistan, after Duncan Fletcher had heard reports he had developed a "doosra" to accompany his regular off-breaks and middle-order batting.
An Old Etonian, he began his professional career at Kent where he stayed until 2004 before moving to Edgbaston.
"I will continue to closely support the club and wish the boys every success for the next season and beyond," said Loudon.
Giles continued: "Alex knows he will always be welcome back at Edgbaston and I wish him all the best for a successful future outside the game."
Warwickshire were relegated in the County Championship and the NatWest Pro40 last summer, and Loudon's departure will cause more headaches.
He had scored three Championship centuries by 1 June last summer.
Bears fans will look for Giles to sign more players, despite Monday's capture of the talented Irish fast bowler Boyd Rankin.