John, who played Jim Branning in the BBC One soap, passed away this morning (12 September) - seven years after a debilitating stroke which left him needing round-the-clock care.
EastEnders released a statement this afternoon, saying the entire cast and crew are "absolutely heartbroken" to learn of his death.
The statement read: "It is with great sadness that we report the death of much-loved actor John Bardon, who played Dot's husband, Jim Branning, from 1996 to 2011.
"Everyone at EastEnders is absolutely heartbroken to learn that John has sadly passed away. His bravery, dignity and courage in battling against the devastating effects of his stroke were admired by all who had the privilege of working with him.
"Loved by us all, John was an exceptionally talented actor whose humour, mischievousness and brilliant performances made Jim Branning one of Walford's most loveable, memorable characters and we will miss John forever.
"Our love and deepest sympathies are extended to Enda, his truly wonderful wife, at this very sad time. May he now rest in peace."
Tonight's episode of EastEnders will be dedicated to John in his memory.
Jim was a regular in the Queen Vic and a keen gambler who fell in love with Dot (June Brown) and married her in 2002. In 2007, Jim suffered a stroke - the storyline was created to account for John's own off-screen illness.
When John was well enough to return to the soap, he continued to feature in the show until 2011. Viewers last saw Jim leave Walford to be cared for in a nursing home. He continued to be referenced in the soap by Dot.