The Ray Donovan actor, 49, shared a cute photo of the family via Instagram on Tuesday, July 25. "Happy Birthday Big Boy! Finally hit the double digits!" he wrote.
In the pic, the Gypsy actress — who is dating her costar Billy Crudup — and Schreiber help to cut the cake. The actors are also parents of son Samuel, 7.
As previously reported, the pair announced in September 2016 that they were ending their 11-year relationship. Watts, 48, opened up about the split two months later.
"I feel I'm in a good place in my life and I want to make sure my kids are healthy, my kids are happy and things are going to go well. Those are my hopes for me and for all of us," she told Australia’s Daily Telegraph.
Schreiber, meanwhile, broke his silence during an appearance on CBS This Morning in December. "We’re parents together, so we’ll be together for the rest of our lives no matter what, and we’re very close. Hopefully that never changes, and I don’t think it will," he said.
Watts and Schreiber began dating in 2005 after meeting on set of The Painted Veil.
Want stories like these delivered straight to your inbox?
For the latest celebrity entertainment, news and lifestyle videos, subscribe to Us Weekly's YouTube Page!