The Miss Congeniality actor, 42, reluctantly agreed to go along with the prank as a personal favour to the talk show host.
Bratt says, "I got asked to do something that I was initially reluctant to do, but you don't want to refuse Oprah."
A woman had contacted Winfrey to say her niece was a big fan of Benjamin Bratt, in order to score tickets to the show.
Winfrey decided to surprise the woman's niece with a spa day at a local hotel and a personal massage from her favourite star.
The TRAFFIC star says, "I had dread in my soul because I knew it wasn't going to work. I said 'All right, I'll do it.' I went out and I said, 'Hi, I'm Benjamin, I'm meant to give you a massage today.'
"She had no idea who I was. Her aunt lied. She just said that to get a ticket to the show. So, needless to say, they buried the piece and it never got shown. It was pretty bad."