The 25-year-old took to the stage at Los Angeles` Hollywood Bowl at a gig to mark Clinton`s belated 65th birthday and the 10th anniversary of his Clinton Foundation, reported Daily Mail.
Gaga wore her hair in blonde curls and sported red lipstick in honour of the late screen icon, before serenading him in a moment reminiscent of the night Monroe sang to President John F Kennedy.
The singer changed the words of her hit track `Bad Romance` to `Bill Romance` in honour of the former president.
"First real Marilyn moment. I always wanted to have one, and I was hoping that it didn`t involve pills and a strand of pearls," Gaga said.
Clinton joked to the crowd, "How cool is it to be 65 and you get Lady Gaga, come on?… And then I wondered… she said she was going to have a Marilyn moment, I thought, `By God I get Lady Gaga and I will have a heart attack celebrating my 65th birthday."
Other performers at the show included Kenny Chesney, Usher and Stevie Wonder.