The 55-year-old actor has reflected on his paranormal experience during a game of 'True Confessions' with 'Bad Boys: Ride or Die' co-star Martin Lawrence on an episode of 'The Tonight Show Starring Jimmy Fallon'.
Reading out his card, Will said: "I once had to emergency check out of a hotel because of a ghost."
As part of the game, each of the trio read out a supposedly true fact as the others tried to figure out if they were telling the truth.
The 'King Richard' actor added: "This was probably 27 years ago."
Jimmy asked for more details about why Will felt the need to check out of the room so abruptly.
He continued: "The ghost urinated in my friend's toilet. And cleared all of his messages from his phone... It was the Lanesborough Hotel in London."
The late-night chat show host jokingly asked if it was "a British ghost", but Will said they "didn't hear it talk".
He recalled: "We assumed it was British. But it was scary enough for us to check out of the hotel."
Jimmy then wondered if the Hollywood star believes in ghosts, and he played things coy with his answer.
He said: "I believe that there are things that you don't understand, Jimmy."
The host and Will's co-star Martin deliberated on whether or not he was telling the true, and his friend believed him.
He explained: "Will, his life has been an adventure. I gotta go with my ride or die — I say true."
Will revealed his story was "100 percent true", which actually surprised Jimmy and Martin.
Elsewhere in the game, Martin revealed he was approached to star in 'Rush Hour' with Jackie Chan, but rejected the role which eventually went to Chris Tucker.
After confirming it was true, he added: "I was happy for Chris.
"That was what it was supposed to be — Chris Tucker and Jackie Chan. And they brought [out] a beautiful franchise with 'Rush Hour.' "