Fisher's brother Todd and her daughter Billie Lourd were in attendance. Other notable guests included Meryl Streep, Courtney Love, Ellen Barkin, Gwyneth Paltrow and Ed Begley Jr.
The service took place at the compound where the late stars lived next door to each other.
The two are expected to be buried together on Friday at Forest Lawn Memorial Park in Los Angeles. Todd Fisher told ABC News the burial site was chosen when hummingbirds appeared at a particular spot.
“My mother loves hummingbirds, and had hummingbirds in her yard,” he said. “We were going all over the place, and we got to this one place to look at this one thing, these hummingbirds came, and it was just like ‘fait accompli,’ as my mother would say.”