The model confirmed their relationship with a series of snaps on Instagram.
After posting a photo of herself and Grainge late last month, Richie shared more intimate photos of her man, including a snap of them smooching. Grainge is the founder and CEO of independent record label 10K Projects, which he started by signing Trippie Redd and Tekashi 6ix9ine. His father is Lucian Grainge, the Chairman and CEO of Universal Music Group.
The 22-year-old shared more photos of herself and the music executive on her Instagram Story looking lovingly at each other.
Earlier this week a source told ET that the model was dating Grainge. "They have been friends for years and Elliot is also close with Sofia's brother, Miles," the source said of Riche's 26-year-old brother. "It's very nice for Sofia to date someone who her family approves of and likes."
"Sofia and Elliot are happy together and having fun," the source added.
In October, a source told ET that Richie and Disick called it quits, in part, because the model wasn't ready to be a stepmom to his three kids with Kourtney Kardashian -- Mason, 11, Penelope, 8, and Reign, 6 -- and that she wanted to take some time to focus on herself.