He recently adopted a young pit bull who was rescued shortly after Hurricane Harvey by the group A Chance to Bloom Dog Rescue.
The dog, who is now named Kuma, was shy, mangy and had medical issues, the rescue said on Instagram.
She was then saved from euthanasia and passed basic obedience training.
The group explained that it had been communicating with their high-profile adopter since March, not knowing that it was Theroux.
This past week, Kuma was transported from Conroe to New York City, where she's living it up in the Big Apple.
Theroux posted on Instagram about his new furry friend thanking all the organizations that helped make Kuma's adoption possible.
"You are the heroes who took Kuma from death and loved her back to life," he wrote about A Chance to Bloom.
Theroux said you can also visit A Chance to Bloom's website to make a donation in Kuma's name.