Firefighters responded to the home at 1607 Nueces Street, northwest of the intersection of Lavaca Street and 15th Street, at around 4:30 a.m.
The fire was brought under control in approximately 20 minutes, fire officials said.
According to the Austin Fire Department, the flames appeared to have started in a crawl space under the office where a homeless camp exists, officials said. No one was injured in the blaze.
The cause of the fire is under investigation.