In case any viewers didn't know Mills's story, host Tom Bergeron reminded the audience early in the show that the former model, whose left leg was amputated below the knee after a 1993 motorcycle accident, was "our first performer with an artificial limb."
Mills, who is in the midst of a divorce from Paul McCartney, and Roberts performed next to last on the live two-hour broadcast, and received kind notes from the panel of three judges.
"You've got more guts than Rambo," said Bruno Tonioli. Len Goodman told the pair: "There was far more right about that routine than was wrong." Their routine ultimately scored an 18 out of 30.
Mills, 39, said she hoped her participation in the contest would inspire others. "A little kid sitting there who's just lost a limb," she said, "I hope they're gonna go, 'Oh, I can.' "
She has always spoken frankly about her disability, and in February told TV's Extra about joining DWTS: "I'm quite happy to be thrown around, and hopefully my leg will stay on." She added, "It's very unlikely my leg is going to fly off, although it would be quite funny."
This is the fourth season of the ABC contest. Other celeb competitors include Ian Ziering, Joey Fatone and Billy Ray Cyrus.