Coolio's manager, Jarez Posey, said the rapper's family had been informed on Thursday by the Los Angeles County Coroner's Office that the singer had died from a fentanyl overdose.
The coroner's office did not immediately respond to a request for comment from Reuters.
Mr Posey said the rapper's children planned to honour their father in future documentary and film projects.
Born in Pennsylvania in 1963, Coolio began performing as part of the West Coast hip-hop scene after moving to Compton, California.
He released his debut album, It Takes a Thief, in 1994, scoring a Top Ten hit with the single Lakeside.
'Gangsta's Paradise' rapper Coolio has died aged 59. He was reportedly found dead in the bathroom of a friend's house on Wednesday afternoon. AFP
Coolio performs on day three of Riot Fest in Chicago earlier this month. AP
Coolio and his granddaughter Arya Ivey perform at a basketball game in Las Vegas in May. AFP
The rapper performs a set at Groovin The Moo 2019 in Canberra, Australia. Getty Images
Coolio and his wife at the Venice Carnival in Italy in 2008. EPA
Born Artis Leon Ivey Jr on August 1, 1963 in Pennsylvania, the artist spent most of his life in Compton, California. Getty Images
Coolio s at the 2003 Radio Music Awards in Las Vegas, Nevada on October 27, 2003. Reuters
With sons Melan, left and Darius at the Los Angeles premiere of 'Harry Potter and the Chamber of Secrets' in 2002. Reuters
A Fender Stratocaster guitar decorated by Coolio. Getty Images
Coolio directs his first music video for Nickelodeon's 'Kenan and Kel' in June 1996. Reuters
Coolio soared to global fame in 1995 when he released 'Gangsta's Paradise'. Getty Images
Donny Osmond and Coolio exchange pose together at the Toyota Celebrity race in Long Beach in April 1999. Getty Images
Coolio accepts his Grammy for Best Rap Solo Performance in 1996 in Los Angeles. Reuters
He also won an MTV Video Music Award for best rap video in 1996. Reuters
Stevie Wonder performs with Coolio in 1995, when the rapper won the Billboard Music Award for best single. Reuters
'Weird Al' Yankovic sports Coolio hair at the American Music Awards 1996 in Los Angeles. Reuters
Bjork and Coolio present an MTV Video Music Award in 1994. Reuters