The fire was reported at a one-story building near 80th and San Pedro streets around 1:36 a.m. by a passerby who reported seeing smoke.
According to police, the building was a house that had been converted into an auto repair business with living quarters. There were no smoke alarms or sprinklers present, police said.
Officials fought to control the flames but found the body of a man inside the front doorway. He was pronounced dead at the scene.
The front door had a difficult lock for firefighters to breach, the department said.
No other injuries were reported.
The victim has only been identified as a man in his 30s. The cause of the fire remains under investigation.