Alfie Yates, who has Duchenne muscular dystrophy, heroically spent more than four hours finishing ‘Move a Mile for Muscles’ at Gold Acre Park in Leeds.
His rare and incurable muscle-wasting condition will mean that by this time next year he will need a wheelchair full-time.
And this summer Alfie had to spend eight weeks in a brace after breaking his leg playing football.
Mum Rachael Yates, 40, of Southway in Horsforth, said: Alfie’s a very determined young man facing a very difficult life-limiting condition.
“He intended to try and walk a marathon over the space of the summer taking a mile at a time, but broke his leg in May.”
After a summer of physiotherapy the Leeds Grammar School pupil, 10, instead decided to walk the ‘Move a Mile for Muscles’ event with Mrs Yates and his dad Sam.
Lawyer Mrs Yates said: “I thought it was highly unlikely because he was still unable to walk around the house.
“Everyone else did it in about half an hour, but he’s very proud of himself.
“I have never seen such grit and determination as I did that afternoon.”
After starting the mile on September 18 holding his mum’s and six-year-old brother Oli’s hands, Alfie took four hours and 15 minutes to cross the finish line.
“It was a huge, huge achievement and took a massive amount of determination,” said Mrs Yates.
There are currently only about 2,500 in the UK living with Duchenne.
The walk raised cash for Muscular Dystrophy UK.
Kirsty Christmas, regional development manager for the charity, said: “Alfie is an absolute inspiration to everyone who meets him.
“Despite having an extremely debilitating condition, Alfie always has a smile on his face and is tough and committed.
“I’m so proud to work with him.”
Mrs Yates will run next year’s London Marathon for Muscular Dystrophy UK in Alfie’s honour.
The youngster has so far raided £320 of a £2,000 target after the Leeds event.
To donate, visit https://www.justgiving.com/fundraising/Rachael-Yates-40