Cyrus, 26, and Simpson, 22, grabbed a bit to eat with Tish in Los Angeles on Saturday.
The "Mother's Daughter" singer was dressed down in a pair of jeans and a T-shirt, with Simpson sporting a similar look, in pictures shared by TMZ. Tish also opted for jeans and an AC/DC shirt.
On Friday, Simpson confirmed the romance telling reporters at a Tiffany & Co. event: “I’m very happy. We are very, very happy,” Simpson said per People. “She’s creative. She’s very passionate about what she does, and I’m very similar in that sense. That’s why we get along so well.”
The singers were outed as an item earlier this month when the pair were caught smooching at a store in Los Angeles.
Cyrus split from Hemsworth, 29, in August after just seven months of marriage. As the news of her divorce broke, Cyrus was spotted on an Italian vacation with reality TV star Kaitlynn Carter, who in turn had just split from her husband Brody Jenner.
Carter, 31, and Cyrus called it quits in September after just over a month of dating.