"It is with great sadness and a heavy heart that I have decided to end my six year marriage to Ashton. As a woman, a mother and a wife there are certain values and vows that I hold sacred, and it is in this spirit that I have chosen to move forward with my life," Moore said in a statement released through her publicist.
So far the reason for their split is based solely on speculation. For years they've been one of Hollywood's "it" couples, but in recent months their relationship became tabloid fodder as rumors swirled about Kutcher's alleged infidelity.
"It was somewhat surprising to see Demi say that she was going to file for divorce," said US Weekly Entertainment Director Dina Sansing. "We had seen a lot of controversy, a lot of speculation on whether or not they were going to stay together, but things had really started to settle down."
Moore is 49 and Kutcher is 33, making for a 16-year age gap between them. They were married in September 2005. Moore said in a 2007 Vanity Fair interview that her relationship with Kutcher caught them both by surprise.
Kutcher received a lot of publicity earlier this year when he replaced Charlie Sheen on TV's hit sitcom "Two and a Half Men."
But recently, all the media attention surrounding him has not been positive and no doubt put on a strain on his marriage.
"The last few months we've heard a lot about Ashton's infidelities. In fact, one of his alleged mistresses spoke to US and said that she indeed did spend the night with him, they did have sex. People have been talking a lot about what's involved in their marriage," Sansing said.
The couple frequently used Twitter to communicate with each other as millions of fans followed along.
Moore was previously married to actor Bruce Willis for 13 years. They had three daughters together - Rumer, Scout and Tallulah Belle - before divorcing in 2000.
Willis later married model-actress Emma Heming in an intimate 2009 ceremony at his home in Parrot Cay in the Turks and Caicos Islands that attended by their children, as well as Moore and Kutcher.
The Associated Press contributed to this report.