Rumer is Demi Moore’s daughter from her second marriage, to actor Bruce Willis, while Kutcher was her third husband.
The former couple did not have any child.
Kutcher, 37 praised 26-year-old Willis on Facebook along with a link to her piece on bullying and body image, reported Aceshowbiz.
“It is amazing that you are telling your story and speaking up for other woman,” Kutcher, who has a baby daughter with his current partner Mila Kunis, wrote on the social networking site.
The “Dancing with the Stars” winner revealed in the essay that she was growing up struggling with body images.
“When you grow up in the public eye the way that I did, everyone is looking at you and waiting for you to do something crazy or say something wrong or have a meltdown,” she wrote.
This is not the first time when Kutcher has lent his support for Willis.
The “Jobs” actor encouraged fans to vote for Willis while she was competing on the dance show.