The Sunderland fan was diagnosed with neuroblastoma - a rare type of cancer - when he was 18 months old.
Bradley went on to be the club's mascot and
became "best mates" with his hero, striker Jermain Defoe.
A minute's applause for the youngster took place just before the kick-off in the club's friendly against Bury at Gigg Lane.
Bury's chairman also said all gate receipts from the match will go to Bradley's fundraising campaign.
His death was confirmed on social media by
The posting read: "My brave boy has went with the angels today.
"He was our little superhero and put the biggest fight up but he was needed else where. There are no words to describe how heart broken we are."
Bradley's mum Gemma had previously said
his In a statement Sunderland FC extended its "'love and support" to Bradley's family.
It said: "He had a special relationship with
Jermain Defoe and their feelings for each
other were evident for all to see. Jermain,
naturally, is heartbroken."
Bradley underwent treatment and was in remission, but relapsed last year.
Well-wishers raised more than £700,000 in
2016 to pay for him to be given antibody
treatment in New York, but medics then found his cancer had grown and his family was informed his illness was terminal.
In December, Bradley's parents Gemma and
Carl, from Blackhall Colliery, County Durham,
were told he only had "months to live".
Four months later they were told the latest and final round of his treatment had failed.
He underwent "tumour-shrinking treatment" at
Newcastle's Royal Victoria Infirmary but the
cancer continued to spread.
On 24 May, Mrs Lowery said Bradley had left
hospital to start palliative care at home, adding more tumours had been found and further radiotherapy was planned.
Then, on 28 June the family wrote on Facebook: "Bradley is deteriorating fast, his temperature is going very high his breathing very fast his oxygen levels low.
"He is sleeping most the time apart from odd
times awake. We knew this was coming but
we are heartbroken beyond words."
On Thursday, Defoe broke down in tears
during a press conference for his new club
and said the six-year-old would "always be in