The pregnant star, who used to date MACaulay Culkin, admits she was never one to dream about her big day, but everything changed when she finally began dating Kutcher in 2012, 14 years after meeting on the set of the Tv sitcom.
They became engaged earlier this year (14) and are now preparing to start a family.
She tells America's W magazine, "I never wanted to get married. From the age of 12, I prepared my parents for no marriage. Then things changed - I found the love of my life."
However, Kunis insists the private couple will be keeping their nuptials low-key: "Now my theory on weddings is: Don't invite anyone. Do it privately and secretly. My parents are Ok with that. They're just excited that I said yes."
In the candid interview, the mum-to-be also confesses she was attracted to Kutcher from the moment she laid eyes on him, saying, "We all get movie star crushes. I'm marrying mine."
And Kunis reveals she was lucky enough to enjoy her first kiss with her future husband, explaining, "My first real kiss ever was with him on the show. And when That '70s Show had a prom, my date for the prom turned out to be my fiance. We can honestly say that we went to prom together."
She adds of the hit comedy: "Not only did it introduce me to my fiance, but I'm so grateful that all my mistakes are recorded for posterity. I went through everything embarrassing that a girl can go through in front of my fiance. There's no question that he's seen the worst. I find that comforting."
The marriage will be Kunis' first and Kutcher's second; he was previously wed to actress Demi Moore. The former couple split in late 2011, months before the actor reconnected with Kunis.