The couple have a 3-year-old son together. Simmons has two daughters with her ex-husband, hip-hop mogul Russell Simmons.
"Djimon walked out on Kimora," a source told the newspaper, adding the split may have happened after Simmons' ex-husband recently stopped funding her expensive lifestyle.
"Kimora lives as if she's the queen of England," the insider said.
"[Hounsou] is a calm, super-nice person and she's such a diva," the source said. "I couldn't believe they got together in the first place."
The Daily News said representatives for Simmons and Hounsou neither confirmed nor denied their breakup when asked for a comment.