A friend had called police to say he was unable to get into the home in the trendy SoHo neighborhood. There was no evidence of foul play, and a medical examiner will determine the DJ's cause of death.
DJ AM, whose real name was Adam Goldstein, had talked openly about past addictions to crack cocaine, Ecstasy and other drugs, but he claimed he had been drug-free for years, even swearing off cigarettes.
His spokeswoman, Jenni Weinman, said the circumstances surrounding his death were unclear. She pleaded for privacy for his family.
In October, MTV was to debut his new reality show, "Gone Too Far," in which he and concerned families staged interventions for drug abusers. In a recent interview with the AP, he talked about holding a crack pipe for the first time in years for the show and said he felt as though he had an angel on his shoulder for surviving so much turmoil.
Last year, he was badly hurt in a South Carolina plane crash that killed four people and seriously injured rock musician Travis Barker.
MTV did not have an immediate comment on whether the show would air.
Goldstein, 36, was a deejay for hire who performed at Hollywood's most exclusive parties and was admired by music aficionados. He also was famous for past relationships with the reality TV star Nicole Richie, the daughter of singer Lionel Richie, and with actress-singer Mandy Moore.
Goldstein was critically injured last September when a Learjet crashed on takeoff in Columbia, S.C. The plane was transporting Goldstein and Barker, a drummer for the pop punk band Blink-182, after a performance; the pair had formed the duo TRVSDJ-AM.
Barker and Goldstein were burned, though Barker was injured more severely. Goldstein had to get skin graft surgery, but about a month later he was performing again, joining Jay-Z on stage.
At the time, he told People magazine he was grateful to survive. "I can't believe I made it," he said. "I've prayed every night for the past 10 years. There's a lot more to thank God for now. ... I was saved for a reason. Maybe I'm going to help someone else. I don't question it. All I know is I'm thankful to be here."
Goldstein rose to fame several years ago as highly sought-after DJ whose beats kept the dance floor packed and clubgoers hypnotized. He was known for his deft mashups, a blend of at least two songs, and performed not only in clubs but on grand stages, performing earlier this year at the Coachella music festival in Indio, Calif.
He was to be one of the playable characters in Activision's "DJ Hero," a rhythm video game from the makers of "Guitar Hero" that uses a turntable-shaped controller. The game is set for release Oct. 27.
"We are deeply saddened by the loss of DJ AM, who was a tremendous talent, a trusted partner and friend to 'DJ Hero,"' said Tim Riley, vice president of music affairs for Activision. "Our thoughts and prayers are with his friends and family. AM was instrumental in the making of 'DJ Hero,' and we hope that his work on the game will be a fitting tribute to his creative spirit and musical talent."
Celebrities and fans instantly shared their reactions to his death on Twitter, where "RIP DJ AM" was the No. 1 topic Friday.
"I'm stunned. Rest in peace Adam," singer-songwriter Josh Groban posted.
"I'm sorry to loved ones," musician and video director Pete Wentz wrote. "So unexpected."
Singer John Mayer wrote: "We're supposed to lose our friends to time, at an age when we're ready to agree to the terms of having lived a long life. Not now."
Representatives for Moore and Barker didn't immediately return telephone messages seeking comment on the DJ's death.
Associated Press writers Virginia Byrne in New York and Michael Cidoni in Los Angeles contributed to this report.