The actor forwarded the photo, which shows the singer exposing her fishnet-clad bottom from under a bed, to Lily, the daughter she shares with Michael Sheen.
Beckinsale then posted screenshots of their message exchange on her Instagram page, captioned: “Lily had a fright. God bless Madonna.”
Madonna recently posted a series of photographs that showed her posing partially nude in various positions in a bedroom.
Pretending one of the images was of herself, Beckinsale asked her daughter: “Do you think this is too much? Thing is my ass looks good.”
Lily, 22, then responded saying: “I’m a little confused I must say.”
Beckinsale later revealed that the picture belongs to Madonna, much to Lily’s relief.
“Like I’d ever,” Beckinsale said, adding: “I can’t believe you don’t recognise your own mother’s anus from under the bed.”
Lily said that a colleague came to check on her when she was worrying about the picture, but after her mother revealed it was a prank, Lily said she cried “tears of happiness”.
She said: “I wouldn’t even be embarrassed like for me if u posted that, I would be concerned.”
Additional reporting by Press Association