The 29-year-old’s family had been desperately searching for him after he was unaccounted for following the attack on Monday (22 May) at Manchester Arena.
However, Martyn’s close friend Russell Hayward confirmed he had been killed in the blast, in a tweet posted on Wednesday morning.
Grimmy - host of The Radio 1 Breakfast Show - later shared some poignant words on his social media accounts about Martyn, following news of his death.
He wrote: “Really very sad to head that Martyn Hett was one of the victims of the attack in Manchester. We were only talking about how funny he is just the other day in the studio.
“From his mum stories, Corrie love, The Audrey Roberts Noise and his Deidre Barlow tattoo, he made me laugh every day with his hilariously witty tweets. What a character! He made a lot of people smile.
“Wanted to send lots of love and energy to his family and friends in Manchester.”
Martyn was a self-confessed ‘Coronation Street’ obsessive, and his fandom had seen him go viral many times over the years - most notably with his creation of ‘The Audrey Roberts Noise’ video, and his Deidre Barlow tattoo on his leg.
The ITV soap also shared a tribute to Martyn on their Twitter account, writing: “Our heartfelt condolences to the family and friends of Coronation Street Superfan @martynhett #WeStandTogether.”
He previously appeared on ‘Come Dine With Me’, and the Channel 4 cookery competition’s Facebook account also shared a tribute to Martyn.
“The ‘Come Dine With Me’ team remember Martyn as a wonderful contributor,” they wrote. “Our thoughts are with his family and friends at this very difficult time.”
Martyn is one of 22 people who were killed in the attack, which took place at an Ariana Grande concert in the city.
He was due to take the trip of a lifetime just two days after the tragedy, to travel around the US for two months.