The beloved mother and daughter actresses died last week, just one day apart. Reynolds was 84 and Fisher was 60.
Ellen Barkin, Ed Begley Jr., Courtney Love and Meg Ryan were among the celebrities who came to pay respect in the private ceremony at the family compound on Coldwater Canyon in Beverly Hills.
Todd Fisher said his mother suffered a massive stroke at home.
"She said she missed her daughter and wanted to see her again. I don't think she meant it quite like that, but within 30 minutes, she went to go see her again," he said.
He said his sister and mother both loved a good party, so the event was meant to honor them.
Todd Fisher said the family will plan a public memorial for fans to attend.
Also, New York City theaters are expected to dim their marquee lights on Friday in honor of the two, who both made their Broadway debuts in 1973.