Holmes was glowing in a forest green sheath dress with black pointed-toe heels. The brunette beauty had her hair curled and down and was rocking a berry lip.
The All We Had star was later spotted cheering on Sloane Stephens and Venus Williams at the US Open Tennis Championships.
Holmes' outing comes after pics of her and Foxx holding hands and smiling while taking a walk in Malibu, California, surfaced online. The pair has been a rumored couple for years, but the pictures seem to prove that they are officially more than friends.
An eyewitness told ET on Wednesday that "Katie and Jamie seemed to be pretty cautious about being spotted together, but were having fun. They seemed to really appreciate every moment together because Jamie did not leave her side. They held hands as they walked on the beach and seemed really relaxed and playful."
See more of the adorable lovebirds in the video below.