Kunis and Kutcher met on the set of the Fox comedy in 1998 where they played love interests Jackie and Kelso. The pair began dating in 2012, though Kunis brushed off the rumors as "absurd" initially.
But once the pair went public, Kunis, 30, and Kutcher, 36, didn't hide their romance and were never afraid of a little PDA. So it comes as no surprise that the actress didn't shy away from showing off a massive diamond ring on Thursday while shopping with her mother.
The couple's engagement comes a few months after Kutcher's divorce from Demi Moore was finalized, two years after they initially separated. This will be the first marriage for Kunis.