The 63-year-old suffered a stroke in August last year and had spent the past 10 months recovering in preparation for the British reggae group’s forthcoming UK tour.
The tour, which includes an all-day event at Sandwell Valley Country Park on August 1, is set to go ahead as planned with the band imminently preparing to announce a new singer.
Campbell said: “Unfortunately, due to continued ill health, I have reluctantly decided to retire from the band so as to focus on my recovery.
“I am very grateful, and would like to express my sincere thanks to the fans for all their support during this time and indeed throughout my time with UB40.
“The band have my full support going forward and, of course, my very best wishes for the future with their new singer.”
Campbell’s older brother and bandmate Robin said on behalf of UB40: “We’ve been rehearsing with every intention of Duncan’s return to performing, but sadly, after suffering further illness, he has made the decision to retire from music in order to concentrate fully on his recovery.
“While we are deeply saddened, we completely understand and fully support his decision. As far as touring goes, we are ready to hit the road for our upcoming summer shows and will be announcing our new frontman imminently.”
Campbell replaced younger brother Ali as lead singer of the chart-topping group in 2008, after Ali quit over a disagreement about management.
UB40 formed in 1978 in Birmingham, choosing their name as a reference to a form issued to people claiming unemployment benefits at the time.
The band produced hits including Red Red Wine and Falling In Love With You and its line-up remained stable for 29 years until January 2008, when frontman Ali left the band.
Ali has been highly critical of his replacement and said watching his brother perform the band’s songs “makes my skin crawl”.
He has since toured as part of the breakaway group UB40 Featuring Ali, Astro & Mickey.
UB40 have scored more than 40 top 40 songs in the UK and are recognised as one of the country’s most successful bands.
They released collaborations album Bigga Baggariddim last week, which features reggae artists from around the world including New Zealand’s House of Shem, India’s Reggae Rajahs and British artist Tippa Irie.