The youngster, known only as Haroon, made the shocking declaration in a classroom in London after becoming obsessed with the sick Islamist killers.
He watched video clips of ISIS prisoners being beheaded, set on fire and learnt the names of the evil organisation's top commanders.
The youngster, now 10, was driven to ISIS propaganda after being bullied at school.
He was labelled a "terrorist" by classmates after telling his school about his love of ISIS.
Haroon began researching ISIS after the Paris terror attacks in November 2015.
He firstly read BBC articles about the terrorist organisation then watched a Channel 4 documentary.
But he soon fell into some of the darkest corners of the internet and watched sick torture and propaganda videos.
Haroon even played an ISIS video game in which players much stage an attack on an airport.
The child said: "It had brutal executions then burning people. It showed people lined up in chains then they burnt them."
After his alarming confession in school, Haroon was referred to the Government's Prevent programme, aimed at fighting radical extremism.
His caseworker, known only as Marion, who works in the borough of Kensington and Chelsea, said it is important to tackle radical beliefs before any serious harm is caused.
She said Haroon was too young to pose a serious threat, but could have fallen into the hands of older ISIS sympathisers.