"Without a doubt we are only friends. We never even kissed. We've never had an affair," says London, 37, who will be featured with Uchitel, 35, on the fourth season of VH1's Celebrity Rehab with Dr. Drew.
The Party of Five actor acknowledges he and Tiger Woods's alleged mistress have become close since they both checked into a Pasadena recovery center – but the two are "like brother and sister."
"She's an amazing person and [the media] keeps messing with her," says London, who made news with a bizarre kidnapping incident. "I think I can identify with her because of that."