Kutcher, 36, began dating his 'That 70s Show' co-star Kunis in 2012. They became engaged in February, 2014 and six months later she gave birth to their daughter Wyatt Isabelle on September 30.
Kutcher posted a picture on his Facebook page, which had the following message written on sand "Happy New Year, Love The Kutchers'.
It was reported two weeks back that the couple was planning their impending marriage.
There were also rumours that the duo may have gotten married after Kunis, 31, was spotted wearing what looked like a wedding band along with her engagement ring while enjoying the Los Angeles Lakers game with Kutcher.