The star found himself accidentally drafted into the "Good Vibrations" rockers' line up when he was a regular on two hugely popular U.S. shows - sitcom "Full House" and daytime soap "General Hospital" - in 1985.
"I loved The Beach Boys... I never even dreamed of meeting The Beach Boys, let alone playing with them," he told pop star Kelly Clarkson on her U.S. daytime talk show.
Recalling his first meeting with the band backstage at a show, he added, "The show wasn't over - they were still going to do the encore and I went backstage and all these cheerleaders chased me in there."
"Mike Love turns to my friend and goes, 'Say, who's that?' He goes, 'That's John Stamos, he's on 'General Hospital', and he always has girls chasing him.' And Mike Love, without missing a beat, said, 'Get him on stage!' "
"So I went on [stage] and played [song] Barbara Ann and I've played with them for over 34 years now. What a treat in life. It just makes so many people so happy, and me happy."
In another interview, Stamos recalled his appearance on the band's "Kokomo" music video. "It's all weird! We were doing a special and the main thing was we were doing a version of 'Wipeout' with the Fat Boys, who were a rap group," he told The Birmingham News.
"And it was at the Grand Floridian at Disney World, and what I remember too is we were like the first guests to stay in that hotel," he continued. "We were their experiment - like they were trying out foods on us and still training staff. So we were doing this ABC special and it was this last minute thing: 'Hey can you guys just run 'Kokomo' real fast. We'll put up a couple cameras ...' "
"It really wasn't part of the plan for the day, and we just kind of threw it up there and did it maybe twice," the 57-year-old went on sharing. "It started raining and we went back to the hotel. And that was it."