The 33-year-old Lance Corporal, who wears a prosthetic leg, danced his way to victory with his Strictly professional dance partner Natalie Lowe.
The dance contest, which usually sees celebrities taking to the dance floor, gave six unsung heroes the chance to strut their stuff in the ballroom.
Joining Cassidy were: Anna Kennedy, 54, the founder of a school and charity for autism; Heather Parsons, 53, the founder of a charity to support intensive care patients and their families; Michael Patty, a 57-year-old fundraiser for the Meningitis Research Foundation; Phil Barnett, 54, the founder of theatre company Kidz R Us; and Trishna Bharadia, 35, who was diagnosed with multiple sclerosis in 2008 and now volunteers with several MS charities.
Each contestant was partnered with a Strictly pro and took to the famous Strictly dance floor to perform a routine for both the show’s judges and viewers.
Trishna danced a Jive with Aljaz Scorjanec to score 35 points.
Michael and Aliona Vilani scored 33 points for their Tango.
Heather’s Viennese Waltz with pro partner Ian Waite saw her score 36.
The other couples all scored 40: Phil and Janette Manrara got top marks with their American Smooth Foxtrot; Anna and Robin Windsor secured a perfect 40 with their Charleston; and Cassidy and Natalie got the same marks with their Pasodoble.
When Cassidy heard that he had won, Natalie stopped the gobsmacked former soldier from swearing live on telly by covering his mouth in the Red Nose Day final.
It was an emotional moment as Natalie gushed to the show’s hosts Claudia Winkleman and Tess Daly about her dance partner saying: “He has taught me so many things about life experience, I just want to thank you so much.”
Meanwhile, Cassidy thanked everyone who had supported him…
“My family and friends and especially my wife have been incredible through all of this,” he said. “Thank you very much to everyone.”