According to reports, Duff will play the role of Stacey, a woman who catches Kutcher's character Walden's eye on the season finale of the show, reported Us magazine.
Duff, 25, started her career by playing the title role of Disney Channel's teen comedy Lizzie McGuire. But the actress has been on a break from acting since giving birth to her first child, a son named Luca Cruz Comrie.
The actress isn't the one who ultimately keeps Kutcher's interest on the show. Walden will end up falling for her grandmother, who will be played by 'Taxi and Celebrity Apprentice' star Marilu Henner, 60.