Kutcher, who is best known for starring in the sitcom "That '70s Show" and for producing the practical joke series "Punk'd," is married to actress Demi Moore.
Moore was engaged in the 1980s to actor Emilio Estevez, who is Sheen's older brother.
Sheen was fired from "Men" this year, midway through Season 8, because of his erratic behavior and drug use.
CBS and Warner Bros. said Friday Kutcher will join "Men" regulars Jon Cryer, Angus T. Jones, Holland Taylor, Marin Hinkle and Conchata Ferrell when Season 9 begins taping this summer for broadcast on CBS in the fall.
"I can't wait to get to work with this ridiculously talented 2.5 team and I believe we can fill the stage with laughter that will echo in viewers' homes," Kutcher said in a statement. "I can't replace Charlie Sheen but I'm going to work my ass off to entertain the hell out of people!"
"We are so lucky to have someone as talented, joyful and just plain remarkable as Ashton joining our family," added Chuck Lorre, the show's creator and executive producer. "Added to that is the deep sigh of relief knowing that our family stays together. If I was any happier, it'd be illegal."
"Ashton is a pop-culture triple threat -- film star, cutting-edge producer and a social-media pioneer," said Nina Tassler, president of CBS Entertainment. "He brings creativity, energy and personality to everything he touches. We are thrilled to have him, and excited beyond words for what he brings to the next season of 'Two and a Half Men.'"