Duff, 27, adopted a puppy this week, bringing home a female sibling of sorts for her dog Birdie.
"Thanks to the Poopie Foundation, Birdie & I have a perfect lil rescue pup joining our family! Kennedy!" she shared on Twitter Thursday.
Kennedy, a 9-week-old Chihuahua-pug mix, was part of a litter that had been abandoned at a park in East L.A., according to Melissa Bacelar, founder of animal rescue group The Poopie Foundation.
Duff met three of the dogs from the litter after they were hired for a shoot. "Haylie literally fell in love on set," Bacelar tells PEOPLE. "There was something about the dog's little face. She did not want to part with that puppy."
"She claimed my heart the second I met her," Duff confirmed on Twitter.
After submitting an application and undergoing a home check, Duff was reunited with Kennedy, this time for good.
And, it seems the two new sisters, Birdie and Kennedy, are getting along famously. "They were just in love and everything's perfect," Bacelar says.
Think Duff's puppy is a cutie? Good news: two of the puppies from Kennedy's litter (pictured below) still need homes. If you're interested in adopting one of them, contact The Poopie Foundation.
The Poopie Foundation