Khloe, who has been dating the basketball star since 2016, also took to her Snapchat the same evening to have some fun with filters and to show off her baby bump.
The pair chat intently before she tilts her head to the side and, shielded by the baggy white hood of Thompson's sweater, they appear to share a kiss.
Most recently, Thompson was recorded with his alleged mistress, going into a Four Seasons hotel in NY, around 5 a.m. ET together, according to Page Six.
"I was there and he was on the table right next to us with a group of friends and some girl who he was obviously making out with all night", the submitter said.
The "Keeping Up with the Kardashians" star and boyfriend Tristan Thompson are now preparing for the arrival of their first child, but the duo initially planned to keep things low-key for the first few days.
In the recording, he can apparently be seen kissing one of them on the lips and rubbing his face in the others boobs.
Gossip website TMZ has obtained the footage, which was reportedly filmed in October 2017, when Khloe was three months pregnant.
Witnesses said they spent around four hours at the five star hotel before emerging together with Thompson sporting a different outfit.
"When she spoke to her sisters earlier today, she assured them that this was all a big misunderstanding and that Tristan would be able to explain it". They were talking and being around each other all night.
According to reports, she's since posted: "I'm pregnant too since everything out here", on her story and claimed she's also slept with "1 more" Cleveland Cavaliers player. He was texting and talking on the phone and she was obviously looking over his shoulder. Throughout her relationship with longtime boyfriend Tristan Thompson, she has gushed over how supportive and sweet Thompson has been.
"Everybody knew who he was".
The source, who wishes to remain anonymous, added: "I love the Kardashians and I think it's devastating".
Fans of the reality TV star have now urged Khloe to dump Tristan.
Neither Khloe or Tristan have publicly addressed the footage which has surfaced.