Mr. Obama, who served two terms as President of the United States until 2016, posted the news on social media along with photos of the dog.
The Portuguese Water Dog was a gift to the family of the late Senator Edward M Kennedy, who was a key supporter of Mr. Obama’s 2008 presidential campaign.
The president had promised his daughters Malia and Sasha that they could have a dog after the election.
A second dog, Sunny, joined the family in 2013.
Both were popular with White House visitors, and they often attended public events, such as the annual Easter Egg Roll.
They also met injured soldiers and children in the hospital.
Mr. Obama’s wife Michelle posted about Bo’s death on Instagram, saying, “He was there when Barack and I needed a break, strolling through one of our offices as s ‘he owned the place, a bullet gripped firmly in his teeth.
“He was there when we flew on Air Force One, when tens of thousands of people flocked to the South Lawn for the Easter Egg Roll, and when the Pope came to visit us.
Ms Obama said she was grateful for the time the family spent with Bo due to the pandemic, and said “no one was happier than Bo” during this time.
“All her people were once again under one roof,” she wrote.