The 36-year-old switched from league side Wigan in 2007 and has won international caps in both codes, playing 44 times for England's rugby union side and scoring 20 tries.
Ashton is the record try-scorer in the English Premiership, with 98 tries, and the Champions Cup, with 41 tries.
He joined Leicester midway through the 2021/22 campaign having previously had spells with Northampton, Saracens, Toulon, Sale, Harlequins and Worcester.
In his time at the Tigers so far, he has scored 10 tries in 25 appearances and started on the wing in the 2021/22 Premiership final win over Saracens at Twickenham.
"I've just felt, this season, that my body is not able to do what I want it do any more," Ashton said in a statement on Leicester's website.
"I'm still enjoying the game, enjoying being in and around the team and the game every day, but if I'm not able to keep the standards that I expect of myself, then it's the right time for me to retire."
Leicester interim head coach Richard Wigglesworth said: "Chris changed the game, to put it bluntly. That's the biggest compliment I can give him.
"Coming over from rugby league, at a young age, Chris worked diligently, and has never stopped working, to understand the game and to be the very best player he could be.
"He has got a miles better brain for the game than he will ever get credit for and is one of the most competitive players I have played with and coached."
