Reports of a possible romance between the former That '70s Show co-stars began in April, though the pair have since denied the claims.
Kunis has maintained that she and Kutcher are just friends, adding: "I've never commented on my personal life - I'm not going to start commenting on my personal life now. But it's a friend. A friend is a friend."
According to TMZ, the actors were spotted eating together at an Italian restaurant in LA on Thursday (June 21), and later leaving together in the same car.
Since his split from wife Demi Moore, Kutcher has been linked to several celebrities, including singer Rihanna.
He is currently filming a biopic about the late Apple mogul Steve Jobs.