Sassoon's company, Eden Sassoon Pilates, confirmed the news on Instagram.
"Our leader, #bosslady @edensassoon will be joining The Real Housewives of Beverly Hills. #pilateseveryday Watch #edenslovestory," the post read.
"She's been filming from the start. Not enough drama from her for a full-time housewife role, but just enough for a friend of the show," a source told ET, before adding that this year's cast trip will be to South Africa.
Sassoon joins returning housewives Kyle Richards, Lisa Vanderpump, Erika Jayne, and Eileen Davidson for the upcoming season. Yolanda Hadid and Kathryn Edwards departed the show after season six.
Also expected for season seven is Camille Grammer, who has made appearances on RHOBH since she left as a full-time cast member in 2013. As for whether Grammer plans to come back full-time, she recently told ET to "talk to the higher ups."
"I don't know. We'll see, we'll see," she said in July on whether she'll make a comeback. "You gotta talk to [executive producer] Andy [Cohen] about that."
"Oh, I love being a part of it for what, it's gonna be six, seven seasons," Grammer gushed. "Oh my god, that's a long time! I call it my dysfunctional family, working with these girls -- but no, they're wonderful. I miss them when I'm not around them. They're fun."