The 49-year-old, who split from Kutcher after six years amid claims that the actor cheated on her, said she is happy to have finally found a suitable name, reported Aceshowbiz.
After the change was done, the mother of three wrote "So hard finding a name that was fun somewhat playful and available. So for now it will be @justdemi It could grow on me! Thanks everyone for your help in finding my new name!"
The change came around two weeks after Moore made her return to Twitter last month.
Having been absent from the social networking site for three months, she tweeted on April 15 a photo of herself lying on top of a white bed covers with a caption, "Testing..."
The actress was previously married Freddy Moore and Bruce Willis.