No structures had caught fire at the 2,500 acre estate, Santa Barbara County Fire spokesman Jeff Ross said.
About 100 firefighters were battling the blaze along with water-dropping helicopters, Ross said.
Jackson, 47, was not at the house. He has been living in the Middle Eastern kingdom of Bahrain since being acquitted of child molestation charges in California in June 2005.
In March, Jackson closed the main house at Neverland and laid off several of his employees.