Barack, his wife Michelle and their two daughters Malia and Sasha officially welcomed one-year-old Sunny, named by Michelle for her cheerful disposition, into the family on Monday.
They introduced the puppy with a special YouTube video and a series of adorable photos.
"Sunny was born in Michigan in June 2012, and arrived at the White House today," it was announced on the White House Blog.
"Just like Bo, she's a Portuguese Water Dog, which works great for the Obamas because of allergies in their family. Sunny is the perfect little sister for Bo – full of energy and very affectionate – and the First Family picked her name because it fit her cheerful personality.
"We suspect Sunny will follow in Bo's footsteps and keep the President company in the Oval Office, go for walks with the First Family after their 6:30 family dinner and even jump up on the First Lady's lap from time to time!"
Images on the website show the black dog lounging on the South Lawn with Bo.
Bo joined the Obamas shortly after they moved into the White House in 2009, in keeping with a promise the President had made to his daughters the night he was elected in November 2008.
The canine's official responsibilities include visiting Walter Reed and Children's National Medical Centre and greeting guests during tours and the annual Easter Egg Roll.
But back in October, Michelle revealed that Bo was lonely, telling reporters that she hosted a "doggie play date" because he "doesn't have enough dog interaction".
When Bo joined the First Family, they explained that they picked a Portuguese Water Dog because their younger daughter, 12-year-old Sasha, suffers from allergies and fur from this breed rarely causes reactions.