The 29-year-old socialite, who filed for divorce from husband Lamar Odom in December after an emotional split, has been seen out and about several times in recent weeks with Montana, 29, reported People magazine.
"Khloe is totally with him. She's having so much fun with him. She wasn't sure at first where things would lead but he treats her amazingly. That makes her feel really good. She deserves that," a source said.
The new couple hit a music listening party together on April 9. They followed that up the next evening by going to dinner at Cecconi's with sister Kourtney Kardashian and her longtime boyfriend, Scott Disick.
"She's not taking it too seriously, just having fun," the source said.