The event is to take place at the Freedom Theater at Forrest Lawn Cemetery Hollywood Hills. The beloved actresses were interred at the cemetery earlier this month.
"We will be celebrating their lives with friends, family members, and the people who loved them, you. The service will begin at 1 p.m. and immediately afterwards, those who want to walk to their final resting place are welcome to do so," Todd Fisher wrote on his website.
Carrie Fisher died at the age of 60 on Dec. 27 -- just days after suffering a mid-flight heart attack. Her 84-year-old mother had a stroke while planning her funeral. She died on Dec. 28.