Security staff had to step in to ensure the safety of the stars in the jungle camp after the 1.5 metre carpet python was spotted.
Mark discovered the intruder under his bed as he and his blue team camp-mates tried to settle down to sleep in the Australian jungle.
He and the other contestants - who included McFly's Dougie Poynter and DJ Pat Sharp - were said to have been left "terrified" by the ordeal.
The Only Way Is Essex star Mark at first thought he had spotted a rat. But on closer inspection he noticed the create was being suffocated by the snake.
"Oh my God Dougie, there's a snake eating a rat," he shrieked.
Dougie responded: "I'm scared, what can I do?"
Security then stepped in to capture the snake and moved it to another section of the jungle. The "rat" was later found to be a bandicoot.
Afterwards Mark said: "I thought it was a lizard and then I saw the snake suffocating the rat."
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