The president shared a photo of the dog named Commander, which appeared to be a German Shepard or a similar breed.
“Welcome to the White House, Commander,” Biden wrote.
The puppy was a gift to the president from his family, CNN reported.
The Bidens entered the White House with two German shepherds named Champ and Major.
Champ “passed away peacefully at home” at the age of 13 in June, the president and first lady announced.
Major received additional training to get accustomed to living in the White House after biting two people — a member of the Secret Service and a National Park Service worker — in March.
The Bidens are also expected to bring a female cat into the White House, with CNN reporting the cat is being fostered with acquaintances and is expected to make the move “in the very near future.”