His devastated owner Ashleigh Butler, who won BGT with Pudsey in 2012, announced the sad news via Instagram, saying she was “heartbroken” to say goodbye.
“I can’t honestly believe I am writing these words. My handsome man has gone, and I don’t know what to do without him.
“My heart is broken, and I don’t know how I’m going to get through this. It hurts so much, that my handsome, incredible Pudsey Bear will never be by my side, where he belongs, again.
“We only had 11 years together, but they were the best years ever. He was my one in a billion dog that will never be replaced.”
She added: “I don’t need to write all of his endless accomplishments on here to prove how incredible he was for me.
“Sleep tight my handsome man, I love you lots xxxx.”
Judge David Walliams gushed at the time: "The nation has fallen in love with Pudsey and you too. You are the ones to beat tonight.”
Alesha Dixon said: "You are showing how special dogs are and what you can do with the right owner and love."
Amanda Holden added: "It was unbelievable and sensational. Pudsey is everybody’s best friend.”
Ashleigh exclusively told The Sun afterwards that she would be splitting the half a million pound prize money with Pudsey.
"He was sitting on the bed and I told him: ‘Pudsey, you’ve just won £250,000.’
"He knows that he’s done something good but he doesn’t know what. He wouldn’t know what to spend the money on so I’ll probably have to spend it for him."
Pudsey 'released' his own autobiography called Pudsey: My Autobiodography in 2012, which sold out within three days. A special book for younger fans called A Pup Story was also released.
He even starred in his own film, Pudsey - The Movie, released in 2014.
Talking to The Sun from the movie's set, Ashleigh said: "We weren’t sure how he was going to be making a film, but he’s absolutely loved it. He’s been brilliant. He’s done everything we asked him to. He doesn’t get nervous at all."
The beloved pup was a regular fixture on the red carpet with his doting owner once joking he was a "bit of a show-off".
"He loves a good red carpet and all the photographers," she told The Sun.
“He likes the limelight because he’s a bit of a show-off.”
As well as performing for royalty, penning a book and starring in his own movie, Pudsey also joined Ashleigh on a string of TV shows including Top Dog Model and Super Famous Animals.
Ashleigh has said in the past that Pudsey helped her through tough times when she was a teenager.
She said: "I used to hear them saying, 'Oh, there’s dog girl, all she ever does is hang around with her dogs'. But when I got home if I was down or anything like that, Pudsey knew and he’d come up and sit next to me.
"And I know when he doesn’t want to do something or he’s not himself or feeling right. The hardest thing I’ve found is protecting him from other people.
"Everywhere we go everybody wants a trick."