The world's cutest dog, Boo, was confirmed dead at 12 years old by a post of its owners to his 16 million followers on Facebook on Friday.

The screen shot of the announcement of Boo's death on its owner's Facebook account. (Photo: China Plus)

The post soon became internet sensations when the American owners started sharing the dog's antics of the beloved Pomeranian dog and his companion, Buddy, who died a year ago, on the social media platform.

"Shortly after Buddy died, Boo showed signs of heart issues. We think his heart literally broke when Buddy left us," his owners wrote. "He hung on and gave us over a year. But it looks like it was his time, and I'm sure it was a most joyous moment for them when they saw each other in heaven."

Buddy and Boo pictured as Boo, "The World's Cutest Dog" sighting at a luxury penthouse at Trump International Hotel in Las Vegas on April 28, 2014. (File photo: AP)

After the announcement was made to its Facebook followers, some say they were shocked and burst into tears when hearing the news.

In 2012, Boo was appointed as the Virgin America's Official Pet Liaison and appeared in a series of books and albums, including the 2011 published book "Boo: The Life of The World's Cutest Dog".

"The World's Cutest Dog" , Boo, sighting at a luxury penthouse at Trump International Hotel in Las Vegas, NV on April 28, 2014. (File photo: AP)

"Our family is heartbroken, but we find comfort knowing that he is no longer in any pain or discomfort," they added, noting that Boo "brought joy to people all over the world."