He will play the iconic character for the final time next year after more than 40 episodes of ITV's A Touch of Frost.
Sir David, 68, said the moment had come to hand in his police badge and retire the oldest detective on British television.
"It's time to move on. Frost is getting a little long in the tooth - it's time for Frost to hang up his coat and scarf.
"You wouldn't want me to play Frost in a wheelchair, would you? A sad day for us all," he told a London press conference.
"One doesn't want to go on and on. You don't want to outlive your welcome."
Three new episodes of A Touch of Frost will be screened from next month followed by a final two-part film in 2009.
The script for that has yet to be written, but Sir David said Frost - one of the most popular detectives on TV - would probably not be killed off.
"Perhaps he just retires gracefully, gets the gold watch and walks away from Denton nick, tears all round. He just hangs up his hat."
A Touch of Frost was first screened in 1992 and has been at the top of the TV ratings ever since.
An ITV spokesman said the character would be given "a dramatic and fitting send-off".
But the Only Fools and Horses star insisted he had no plans to retire from acting.
"Hopefully not. I want to be able to do things I believe in - but I'm not going to just stay on and do just anything."
He is also to star in a new ITV1 drama project called Albert's Memorial, which follows the story of three World War II veterans.
Click here to read Ian Wylie's television blog.
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Jay B, oldham (16/09/2008 at 08:54)
but i thought they'd stopped producing this programme years ago. when ever i catch a bit of an episode it looks like its set in the mid nineties judging by the cars on the roads and the clothes people wear.
Donna. Harpurhey (16/09/2008 at 09:44)
Marc (16/09/2008 at 11:56)
Mr Manchester (16/09/2008 at 13:01)
Some salt with get rid of that off your doorstep, Marc.
Jomov (16/09/2008 at 14:35)
Marc (16/09/2008 at 14:39)
the beer baron (16/09/2008 at 15:04)
Marc (16/09/2008 at 15:06)
That one was pretty scary Jomov. Remember the one with the stuffed rabbit? gave me nightmares for days...
Mr Manchester (16/09/2008 at 16:21)
Javier Bardem in No Country For Old MEN had me hiding behind the settee recently too...