ATF agents and officers were seen in the area of Sunset Boulevard and Beverly Glen sorting through and documenting the collection of weapons.
There were a variety of rifles, shotguns and handguns.
The ATF didn't provide details, but said the operation was part of an ongoing investigation with the Los Angeles Police Department.
Authorities served the search warrant early Wednesday after receiving a tip that someone was manufacturing and selling weapons out of the home.
Holmby Hills is a small, wealthy neighborhood in the hills northeast of UCLA that is perhaps best known as the home of the Playboy Mansion.