Son Michael Wilding told the 400 people gathered Sunday in a theater at the Warner Bros. studio lot in Burbank that it was especially meaningful to have so many friends on hand to celebrate his mother's spirit.
The Academy Award-winning star of "Butterfield 8" and "Who's Afraid of Virginia Woolf?" was 79 when she died on March 23 of congestive heart failure in Los Angeles.
Spokeswoman Sally Morrison says Farrell hosted a service, which featured memories of the violet-eyed beauty.
"Virginia Woolf" director Mike Nichols put together a touching video message, grandson Rhys Tivey played "Amazing Grace" on the trumpet and John performed "Blue Eyes."