The fashion mogul, 37, has split from her longtime partner, actor Djimon Hounsou, 48.
"Djimon Hounsou and Kimora Lee Simmons have officially separated after 5½ years," the Amistad star's rep tells People. "Though never married, they have one child together, Kenzo Lee Hounsou, who is 3½ years old."
Over on Twitter, Simmons wrote this: "There have been quite a few hurtful rumors circulating. The truth is Djimon + I have been separated for some time. We have remained happy, loving, co-parenting friends + family. We all have much to be thankful for." Simmons had characterized her relationship with the Academy Award nominee as "kind of" engaged.
Simmons is also mom to two daughters by ex-husband Russell Simmons.