DMX has for years been battling substance abuse and spent several periods in rehab but his lawyer, Murray Richman, said he did not know if the habit is to blame for the heart attack.
DMX, whose real name is Earl Simmons, is a hip-hop icon who has collaborated with artists including JAY-Z, Ja Rule, Eve and LL Cool J as well as appearing in films.
Mr Richman said the 50-year-old was taken to hospital in White Plains, New York late on Friday evening where he is surrounded by his family. Richman said:
He was on life support. He’s been taken off of life support. He is breathing on his own but there is a little brain activity.
Earl is a sweet guy. Earl was a person who could tell such a story. He was a person with such depth. It’s a heartbreaker.
The father-of-15 has in the past served jail sentences on charges including animal cruelty, reckless driving, drug possession and weapons possession.
In 2016 he stopped breathing and had to be resuscitated in a hotel car park in New York state.
DMX has a music career spanning more than 20 years has also appeared in films including Cradle 2 the Grave and Romeo Must Die, both starring Jet Li.
More: BBC News