Khloe, 30, dated the 'Pop That' hitmaker, real name Karim Kharbouch, for eight months earlier this year, reported Contactmusic.
Montana appears to have made amends with the reality Tv star and was photographed attending a Kardashian family party to celebrate Khloe's half-sister Kendall Jenner's 19th birthday.
The reunion comes just days after Montana admitted he was still close to Khloe, stating, "Khloe, my baby. We got a special relationship. We're always (gonna) have that relationship... We talk damn near everyday (sic)."