Decked out in comfy clothing, the pregnant actress kept her baby bump well-hidden with a large bag.
Green, meanwhile, looked to be the ever-protective father as he held the couple's little one close.
In August, Fox's rep confirmed to E! News that the Transformers star was expecting a second child.
Fox and Green tied the knot in 2010, and they welcomed their son last September, though they managed to keep it a secret from the media for three weeks.
Green recently revealed that while he and his wife are "doing great," they're not quite sure how they're going to juggle the new baby and a toddler.
"We honestly have no idea and we discuss it daily and think, 'How are we going to do this?" the former Beverly Hills, 90210 star told People. "I think we'll see when it happens. People do it all the time."