On Monday, Wilmer Valderrama Tweeted a sneak preview of the anticipated reunion, writing, "Yep ... It happened."
Joining him, Kutcher and Kunis for the get-together was costar Laura Prepon.
A source tells PEOPLE that the mini-reunion is expected to air as part of Fox's 25th Anniversary special this Sunday. And according to an EW.com report, castmembers from In Living Color, 24 and Married...With Children are expected to appear on the April 22 show, as well.
As for Kutcher and Kunis, who were photographed furniture shopping in L.A. recently, a source tells PEOPLE, "They have been friends for years."