The "Transformers" star and his pop star wife Fergie took in a canine companion, named Meatloaf, for their dachshund Zoe, reported People magazine.
Duhamel, 39, wants others to consider picking up pets from shelters after he was left shocked by the number of homeless pets in the US.
"Pet adoption changed my life when we were looking to find a companion for our seven-year-old dachshund, Zoe. Soon after adopting Meatloaf, I learned that these pets are just grateful for the love you have to give them.
"I'm shocked by the statistics of the homeless pet problem. I applaud PetSmart Charities for its achievement of saving five million pets, and I'm honoured to work with them to encourage everyone to bring the joy of an adopted pet into their lives and help save millions more pets," he said.