Lane, 46, joins Henry Cavill, who was cast as the Man of Steel in January. Zack Snyder (Watchmen) will direct the film and Christopher Nolan (The Dark Knight) will produce as-yet-untitled film. The film is scheduled for a December 2012 release.
"This was a very important piece of casting for me because Martha Kent is the woman whose values helped shape the man we know as Superman," Snyder said in a statement. "We are thrilled to have Diane in the role because she can convey the wisdom and the wonder of a woman whose son has powers beyond her imagination."
Lane was nominated for an Oscar for Best Actress in 2002 for her performance in Unfaithful. She most recently starred in Secretariat and will appear alongside Tim Robbins and James Gandolfini in the HBO film Cinema Verite, out next month.
Are you excited to see Lane play Superman's mom?