Some of his celeb pals helped him raise the massive sum, with J Lo and Ben Affleck sponsoring him for $78,000 (£46,000) and Jay-Z $25,000 (£15,000).
The money will go to New York schools, children suffering from HIV and Aids and his own social charity.
P Diddy ran the 26-mile race in four hours 14 minutes 54 seconds, coming 11,359th out of 35,100 runners.
Finished in top half
After the race he said: "I definitely wanted to stop," but added that the race was "a life-changing experience" because he kept going.
"Never in my life have I ever experienced anything as crazy as this," he said - adding that he would not be back next year.
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