"I'm still in love with you," she told the 56-year-old actor on stage, in front of a star-studded audience which included Leonardo DiCaprio, Chris Rock, Courtney Love, David Blane, Dave Chapelle, Bethenny Frankel, James Corden, and another one of her exes, Alex Rodriguez.
The two have clearly remained close after their four-year marriage ended in the '80s, as Penn agreed to Madonna's offer, handcuffing her and crawling through her legs in an effort to get the crowd to bid higher.
"For once, he's not the one being arrested," she joked.
The mom of four raised more than $7.5 million for Raising Malawi, the non-profit organization she founded in 2006 that is working to build Malawi's first pediatric surgery and intensive care unit, which will be named Mercy James Institute of Pediatric Surgery and Intensive Care and open in 2017.
Among the rare photographs and tour memorabilia auctioned off throughout the night, Madonna also offered up three black-and-white photos from her 1985 wedding to Penn, shot by the late photographer Herb Ritts, which sold for $230,000.