Khloe Kardashian claims a shady contractor ran off with the deeds to the side-by-side mansions she and Kris Jenner were building … and they’re BEYOND pissed.

Khloe made the revelation on Thursday’s episode of ‘KUWTK’ saying she and Kris don’t currently have any houses because she claims a contractor they ultimately fired not only stole their deeds … but also a lot of their money.

The nightmare appears to have started when Khloe claims she ran a background check on the contractor, and told Kris she was NOT comfortable hiring him … but Kris pushed ahead anyway.

That decision may have come back to bite them hard — Khloe says the guy has their deeds, their money and the project has come to a screeching halt … because they’re not allowed to continue building.

You can see Kris fuming in what appears to be a tense convo with her legal team. But, the fight’s not over. Kris says she wants to do something to make sure this contractor doesn’t swindle anyone ever again … and Khloe says they’re gearing up to sue the contractor’s ass.

As we reported, Khloe and Kris are were building side-by-side modern farmhouses in an exclusive enclave in the Calabasas area. It used to be a 3.4-acre lot for a single property but Khloe and Kris wanted 2 properties and be a stone’s throw away from each other.

It’s unclear exactly how much they paid for the properties … but there are reports they each plunked down north of $10 million