The 'Karma Chameleon' hitmakers were left with no choice but to halt their UK and US run of shows so the 53-year-old frontman can be treated for the growth, which was diagnosed by a specialist in Los Angeles and may require surgery.
In a Facebook post on his personal page, George wrote: ''Due to serious issues with my throat I have been forced to cancel both the US and British tour with Culture Club.
''I have a polyp on one of my vocal cords which has haemorrhaged and one of my vocal cords is unusually enlarged and won't close properly when I sing. In true British fashion I have ignored it thinking the problem might just be tiredness ... I have been advised by doctors that to continue singing with this polyp would further damage my voice and would further damage my voice and could cause irreparable damage. It's a risk I just cannot take.''
George admits his decision has left him ''devastated'' but he has promised fans that Culture Club will be back on the road once his throat is better.
He added: ''I feel gutted to be letting people down. Such support makes my decision so much harder, to say I am devastated barely touches how I feel. I know that those of you who love and support me will understand that this is a decision I just had to make. I will definitely get better and will see you all soon back on tour. Thank you for the love it means everything.''
Culture Club's 21-date tour of Britain and America - kicking off at the Rancho Mirage, in California - would have been the first shows featuring the band's full original line-up since 1986.
Organisers are planning to reschedule the concerts but fans can get a full refund from point of purchase if they wish.
The band will release their first album, 'Tribes', since 1999 in early 2015. They recorded the LP with producer Youth, who has previously worked with Sir Paul McCartney, The Verve and Embrace.
Culture Club - George, Mikey Craig, Roy Hay and Jon Moss - sold in excess of 100 million singles and over 50 million albums in the 1980s and were one of the biggest pop bands of the 80s.