Despite his much troubled childhood, he learned how to read from the Pelton Power Program for Kids at age 12, founded by Texas jazz musician Aaron Pelton. He began performing after graduating high school. After releasing one single, "Watcha Gonna Do", an addiction to crack cocaine derailed his career. After quitting and becoming a firefighter for a brief period, Coolio returned to performing and recorded his debut album. It Takes a Thief was released in 1994. The second single was "Fantastic Voyage", which became a massive nation-wide hit.

"Gangsta's Paradise", a rap written to the tune of Stevie Wonder's "Pastime Paradise" from Songs in the Key of Life, was placed on the soundtrack to Dangerous Minds because executives at Tommy Boy Records felt it would not sell. It ended up being a #1 pop hit in the US, and became the first rap single to sell over a million copies in the UK, where it also reached #1. For that, he achieved history and was the first ever Gangsta rapper to have a UK #1.

"Weird Al" Yankovic parodied the song with "Amish Paradise". Coolio claimed that he was unaware that Weird Al's record label had gotten permission from Tommy Boy Records for Al to do a parody of the song. Coolio made no secret of his discontent, which led to discord between the singer and the record company. A series of photos taken at the XM Satellite Radio booth at the 2006 Consumer Electronics Show suggests that Al and Coolio may have made amends.

After his 1995 hit album Gangsta's Paradise, Coolio continued touring and started acting. His third album, My Soul, was unsuccessful. Legal problems (including thievery) in Germany, and later California put Coolio's career on hold. He appeared in a few films and set up his own record label, Crowbar Records, but his next album was delayed until 2002. El Cool Magnifico included a collaboration with Kenny Rogers on an update of his old hit "The Gambler", however the album as a whole was commercially unsuccessful. He was the singer of the Kenan and Kel theme song. He originally got the name "Coolio" from his mates in Compton when he was younger, who compared his musical talent to that of Julio Iglesias but since he rapped instead of sang, and had a fresh cool mellow feel, he was given the name Coolio Iglesias. He has appeared on songs alongside 2Pac, Busta Rhymes, Method Man, LL Cool J, B. Real, LV and the 40 Thevz.

Other pieces of his work include C U When You Get There, whose melody lines are based on Pachelbel's Canon.

In January-February 2004, Coolio tried to win a record deal on the "Comeback Show" contest on German television, but eventually the group Smokie won it instead of him.

Coolio guest starred in the hit series Charmed, as a Lazarus demon, in the episode Marry Go Round, he also voiced Kwanza-bot, a one-off character featured in the A Tale Of Two Santas episode of Futurama. In fact, according to the DVD commentary, the producers of Futurama were so impressed by his range of voices, that they said he could done voice-over work professionally.