The couple gathered with friends and family including Leah Remini and Benny Medina at singer/songwriter Carole Bayer Sager's home in Bel-Air on Friday, September 27.
"It was a chance for all of their friends in LA to celebrate their engagement," a source tells E! News.
After the celebration, Rodriguez took to Instagram to post about the event.
"So great celebrating with family and close friends last night," he captioned a picture of him and Lopez at the party.
Rodriguez and Lopez became engaged in March.