Former Australia batsman Lehmann arrived at Headingley in 1997 and his 172 on Wednesday in the County Championship match against Kent was his 25th first-class hundred for Yorkshire.
Lehmann had averaged more than 66 for Yorkshire and this season alone he has made five scores of over a hundred.
The 36-year-old Lehmann, who played 27 Tests for Australia, has also been a handy left-arm spinner for Yorkshire where his brother-in-law, Craig White, is the captain and helped the club win the County Championship in 2001.
"I have had some great times playing for Yorkshire over the years and I have been honoured to wear the White Rose of this famous county," said Lehmann.
"I will certainly miss the players, staff and supporters who have been fantastic to me over the years," added the Australian who this year was named in the 'Greatest Ever Yorkshire XI' by a Yorkshire Post readers' poll.
Yorkshire chief executive, Stewart Regan, said: "Darren is not only a fantastic cricketer but also a genuinely nice bloke who is adored by our fans. "His contribution to this club has been immense and he will be sorely missed," Regan added.
"However, he has made it known for a number of weeks that his body was struggling to cope with the demands of a rigorous first-class cricket schedule and this season was likely to be his last for Yorkshire.
"Having made up his mind, we fully respect his decision and thank him whole-heartedly for a magnificent Yorkshire career."