The Two And A Half Men star filed papers last Friday to legally end his marriage more than a year after the couple announced their split in November 2011, after six years of marriage, following his fling with Sara Leal, 22, in San Diego two months previously.
Sources told gossip website TMZ.com that Ashton waited to file for divorce because he was hoping to preserve Demi's dignity by giving her enough time to end things first, but grew tired of waiting when she showed no signs of making any moves to legally end their union.
According to the documents filed in Los Angeles, the 34-year-old actor has cited "irreconcilable differences" as the reason behind their split and is not seeking spousal support.
But the former That 70s Show star - who has been dating his old co-star Mila Kunis, 29, for the past nine months - has not specified that Demi, 50, be denied any requests for her own spousal support.
At the time she announced her separation from Ashton, Demi issued the following statement: "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."
Ashton later posted a message on his Twitter account, saying: "I will forever cherish the time I spent with Demi. Marriage is one of the most difficult things in the world and unfortunately sometimes they fail. Love and light, AK."
Previous reports indicated that the former couple was struggling to reach a financial settlement, but Ashton's papers suggest that their property rights will be worked out later.
Ashton and Demi, who were married in September 2005, have no children together but he is reportedly still close with her three daughters Rumer, 24, Scout, 21, and Tallulah, 18, whose father is actor Bruce Willis.
The girls are said to have recently cut ties with their mother because of her hard partying.