Kunis – who has also worked on MacFarlane's series Family Guy - praised him as one of "the most talented" people she's ever known.
"I don't think there is anything that he can't do. I truly don't," she told The AP. "Of all the people that I know, he is one of the most talented human beings, and not like, talented in the way that he'll try anything. But he'll try and succeed, he's so good."
MacFarlane humorously disagreed with Kunis's assessment by mentioning that he's yet to master one sport.
"I'm a terrible tennis player. Terrible, horrific," he quipped.
The writer added more seriously of his ambition: "I tend to like to try things that I haven't done before, for better or worse. I go into new things not afraid to fail.
"I went into this project [Ted] with that in mind, I went into the album project with that attitude. I like things that scare me a little bit."
Kunis previously said she felt very comfortable in accepting a role in Ted.
Ted is now playing in the US and is released on August 1 in the UK.
Watch a trailer for Ted below: