The 30-year-old beauty - who has been dating the basketball star for six months –went into "shock" when she walked into her Beverly Hills home to see him on one knee holding a 20.5 carat Lorraine Schwartz diamond ring.
She said: "I didn't expect this at all. I was in such shock. I never thought it would happen at home, and I never thought now."
Kris had Kim's mother Kris Jenner on hand to help him pick the ring, and the pair celebrated with all of her family after she said yes.
She added to People magazine: "Kris really didn't want a big celebration, but he had jokingly told my mom he'd be fine if there were mini-horses there.
"Later that night at the party, my mom brought out two mini-horses, covered in glitter, for us. It was hysterical!"
Socialite Kim has previously said she has not been able to find any fault with him since they began dating.
She revealed: "I think I haven't found one thing wrong with him, let's just put it like that."
