Chapman was born in Leicester in 1941 and lived at various addresses in the county, including Burton Road in Melton Mowbray, where the plaque was unveiled.
Chapman, who was the lead in two Python movies, Monty Python and the Holy Grail and Life of Brian, died of cancer in 1989, aged 48.
Fellow Python and friend Michael Palin attended the ceremony.
Chapman attended Melton Mowbray Grammar School before going to Cambridge University, where he became involved with the Footlights comedy club.
Monty Python's Flying Circus was founded around ex-Footlights members and, running from 1969 to 1974, it is widely credited with changing the face of British comedy.
Palin said: "I can almost feel him tittering slightly at all this - but I think he would have been honestly quite chuffed, quietly.
"He was that mixture, like all of us, of not taking things seriously but at the same time taking things quite seriously."
The green plaque scheme is organised by Leicestershire County Council. Previous awards have gone to 19th Century social reformer Charles Booth and Dambusters pilot Geoffrey Rice.
In September 2012, a British Comedy Society blue plaque, to commemorate Chapman, was unveiled at the The Angel pub in Highgate, north London, marking the fact that Chapman "drank here often and copiously".
From:
BBC.com http://www.bbc.com/news/uk-england-leicestershire-30413224