Chadrack Mulo, who was autistic and is thought to have been mute, spent the fortnight alone in their flat unable to get help or feed himself.
He succumbed to hunger and thirst and lay down to die next to his mother’s corpse, where he was found hugging her.
The tragedy has led to questions about how a child could starve to death in Britain in 2016 without anyone noticing.
Neighbours said they were devastated that they had not heard any cries from the "sweet" youngster.
Chadrack’s school had rung his mother and even gone round to her flat, but eventually gave up trying to discover the reason for his long absence.
Now a coroner has demanded a nationwide schools alert system to ensure pupil absences are properly investigated.
The tragedy happened in Hackney, east London, where Chadrack lived with his 24-year-old Congolese mother Esther Eketi-Mulo, who was separated from his father.
Esther died suddenly from an epileptic fit during the weekend of October last year.
Coroner Mary Hassell said: "Chadrack had learning difficulties and when his mother died unexpectedly at home he did not know how to call for help or feed himself properly."
"The likelihood is that Chadrack lived alone in the family home for over a fortnight after his mother’s death. He was found a couple of days after his own death with his arms around her body. She was by then very decomposed."
Staff at nearby Morningside Primary School were concerned by Chadrack’s absence and tried to contact his mother several times, but did not have phone numbers for any other relative or friend.
After a few days, they visited the flat twice to check on the youngster but left when no one answered the door.
Neighbours initially thought the strong odour coming from his mother’s decomposing body was cooking smells, but eventually alerted police when it became too strong.
Officers found the tragic pair on October 20, about 48 hours after Chadrack is believed to have died of malnutrition and dehydration.
Neighbour Justin King, 46, said: "It is so sad. It makes me so upset when I think I could have been his saviour, but I just didn’t think anything was wrong. The police explained she had a fit, banged her head and bled to death."
A 35-year-old neighbour added: "It has haunted me for a long time that I could have helped, and I didn’t know."
"Chadrack needed feeding and watering. He passed away because he was hungry, not because something happened to him. I keep thinking, “Did I hear him?”. But he never spoke. He just hid behind his mum and held on to her clothes. He couldn’t even call out or speak through the letterbox."
The school’s headteacher, Janet Taylor, said: "Chadrack’s tragic death has devastated all those who knew him. We will remember him as a happy little boy."
The school now keeps the phone numbers of three adults for each child, visits immediately rather than waiting up to five days, and calls police if all else fails.
The coroner said this should become standard practice nationwide, and has sent a "prevention of future deaths report" to the Department for Education demanding a response.
A DfE spokesperson said: "This is a heart-breaking case. We will be responding in due course."
Sudden death as a result of epilepsy is believed to kill 600 people a year in England and Wales.