The 35-year-old is keen to pop the question to the 30-year-old, whom he has been dating for over a year, reports contactmusic.com.
Kutcher filed for divorce from Moore last year, but was involved in a bitter legal battle after the 50-year-old actress reportedly asked for an eight-figure sum in the settlement due to Kutcher's involvement in a venture capital fund worth $100 million.
However, Kutcher has now agreed to hand over a chunk of his multi-million dollar fortune to Moore as well as some shares in his technology business.
"Demi and Ashton's divorce has cast a cloud over his and Mila's relationship because it's dragged on for so long. Thankfully Demi's turned a corner. She's no longer bitter and she wants the divorce over and done with as soon as possible so she can get on with her life too," a source told The Sun newspaper.
"She's agreed to a settlement of several million and some shares in Ashton's various technology start-ups after he persuaded her to attend a tech conference with him to see for herself how much they'll eventually be worth. They're all happy and the papers are signed and with the lawyers now, so Ashton's free to officially propose to Mila," the source added.
Meanwhile, Kutcher and Kunis sparked speculation of their engagement four months ago after the actress was spotted wearing a gold band on her ring finger.