"This is a film I want the world to see," she said.
Dressed in Chanel haute couture and heels so high she twice grabbed the edge of a seat to steady herself, the Material Girl, 49, sounded near tears as she stood before the audience (including Sharon Stone) at the special screening.
"It's an incredible opportunity for me to be able to show this film in Cannes," she said, noting that she "held my breath" when she sent it to Cannes festival director Thierry Fremaux. "I think I turned purple," she joked.
"To say that this film is a labor of love is trivial," she said. "It's also the journey of a lifetime. I hope you all are as inspired watching it as I was making it." (The singer's adoption of a Malawian boy, David Banda, is nearly complete.)
One light moment: Fremaux teased her about introducing the film in French "because I know she speaks it."
Said Madonna with a laugh: "Not so good."