Archie Battersbee has died in hospital after weeks of legal battles.
The 12-year-old had been in a coma since he was found unconscious by his mother Hollie Dance in April and was being kept alive by a combination of medical interventions, including ventilation and drug treatments.
Speaking outside the Royal London Hospital in Whitechapel, east London, Ms Dance said her “beautiful little boy” died at 12.15pm on Saturday.
Announcing her son’s death to the media, Ms Dance, of Southend, Essex, said “he fought right until the very end”.
Speaking through tears, she said: “Can I just say, I’m the proudest mum in the world.
“He was such a beautiful little boy and he fought right until the very end, and I am so proud to be his mum.”
Breaking down, she said: “The last however many weeks since 7th April, I don’t think there’s been a day that hasn’t been awful really.”
Ms Dance added: “It’s been really hard. Despite the hard strong face and appearance obviously in front of the cameras up until now, I’ve been pretty broken.”
Asked if there was anything more she could do, Ms Dance said: “No. I’ve done everything that I promised my little boy I’d do. And I’ve done it.”
Alistair Chesser, chief medical officer at Barts Health NHS Trust, said: “Archie Battersbee passed away on Saturday afternoon at The Royal London Hospital after treatment was withdrawn in line with court rulings about his best interests.
“Members of his family were present at the bedside and our thoughts and heartfelt condolences remain with them at this difficult time.
“The trust would like to thank the medical, nursing and support staff in the paediatric intensive care department who looked after Archie following his awful accident.
“They provided high quality care with extraordinary compassion over several months in often trying and distressing circumstances.
“This tragic case not only affected the family and his carers but touched the hearts of many across the country.”
Supporters brought flowers to the hospital on Saturday morning.
Shelley Elias, 43, said she had come to the Royal London Hospital because “I wanted his mum Hollie and the family to know I was thinking of them”.
She said: “I did not know what to write because there are no words that will take the pain away.
“I just wanted the mum and her family to know that I am here for them.
“My boy is 12, the same age as Archie, and this just puts things in perspective. When things like this happen, you just think ‘I have nothing to moan about in life’.”
Candles flickered in the shape of the letter “A” and also formed a love heart around a card with Archie’s name in a makeshift tribute at a statue in front of the hospital.
Andrea Williams, chief executive of the Christian Legal Centre, which has been supporting the family’s case, said: “Our thoughts, prayers and support are with Archie’s family at this tragic moment.
“We will continue to support the family, as we have done throughout, ever since they came to us after being issued with last-minute legal proceedings to remove life support from Archie.
“We are thankful for the widespread public support for Archie and his family. It has been a privilege to stand alongside them.
“The events of the last few weeks raise many significant issues including questions of how death is defined, how those decisions are made and the place of the family.
“No one wants to see other families experience what they have been through. We need to see urgent review and reform of the system.”
Christian Concern said the family had wanted to challenge the High Court ruling by arguing there had been a violation of articles six and eight of the European Convention on Human Rights.
Article six is the right to a fair trial and article eight is the right to respect for private and family life.
A spokesman for the European court said it had received a request from representatives of Archie’s parents under Rule 39, which allows it to apply “interim measures” in “exceptional” cases, and that the complaints “fell outside the scope” of that rule, and so it would not intervene.
The Court of Appeal judges said Mrs Justice Theis’ ruling in the High Court dealt “comprehensively with each of the points raised on behalf of the parents”.
The judges said they had “reached the clear conclusion that each of her decisions was right for the reasons she gave”.
The Court of Appeal judges also said one of the arguments presented by Archie’s parents was “flawed legally”, adding: “It is also not easy to understand as it seeks to argue that Archie’s best interests have ceased to be relevant.”
Doctors treating the schoolboy for the last four months declared Archie to be “brain-stem dead”, prompting a lengthy but ultimately failed legal battle by his family to continue his life support treatment in the hope he would recover.