Thomas Mensforth, known as Mensi and understood to be in his 60s, died in hospital where he had been bravely fighting Covid for some time.
The band’s official Facebook page announced his death on Friday, December 10.
In a post they said: "Today we lost a punk rock legend. Our thoughts are with his family, friends and all those he inspired.”
The band had earlier provided an update to fans on Monday, December 6 after a message from Mensi’s family to say he was in intensive care but was fighting every day.
He was the frontman of the Angelic Upstarts who formed in South Shields in 1977 and were hailed as one of the first street-punk bands.
Mensi and the band had a strong socialist working class and anti-fascist philosophy.
They appeared on Top of the Pops in 1979 singing one of their biggest songs Teenage Warning.
After a brief split they reformed in 1988 and several more times afterwards.
The band continued to perform with Mensi, who was a big Sunderland AFC fan, being the remaining original member.
Earlier this year he was interviewed by Sunderland filmmaker Rob Kilburn of media company Tyne and Weird for a new documentary – Organised Chaos, due out next year – about the North East’s punk scene.
Rob said: “I knew of Mensi, he was quite legendary in punk circles in the North East.
"He played at a lot of North East venues and I think a lot of people will have seen him in their youth.
"He came across as a really genuine person, really sincere. I got the impression he stood up for his values and he was a bit of a working class hero.”
Hundreds of tributes have already been left on the band’s Facebook page.
One fan said: “A principled man with convictions and a voice, you will be truly missed!”
Another described him as a: “Legend and amazing frontman. I'm so sorry!”
A fan sent their condolences saying: “A big hug to his family, his friends and the punk-rock family who lost a great man today.”
Another said: “RIP Mensi...you inspired so many and I will always be an UPSTART”.