Winfrey, 66, took a few steps and then went down while talking about emotional balance at her "2020 Vision: Your Life In Focus" event at the Forum in Inglewood.
She laughed it off as she sat up in the spotlight.
"Shoes," she told the audience.
Longtime partner Stedman Graham rushed from the VIP section, but Oprah remained a trouper, continuing the presentation without shoes."I’m headed home to ice my knee and ankle," she later posted on Instagram.
Click here to follow Daily Voice Middletown and receive free news updates.