Astro, who performed in the reggae pop band for more than 30 years, died after a short illness, his current band confirmed.
"We are absolutely devastated and completely heartbroken," said a statement on Ali Campbell and Astro's Twitter account.
"The world will never be the same without him."
UB40 were immensely popular in New Zealand, with the cover of a Neil Diamond song Red Red Wine going to number one on the local charts.
Astro left UB40 in 2013 and went on to perform with breakaway group UB40 featuring Ali Campbell and Astro, which had played some concerts this year and was due to go on tour in 2022.
The original band broke through in the early 1980s with their unique take on British reggae and found success with hits like Red Red Wine and Can't Help Falling In Love.
They played in New Zealand many times, including on a 40th anniversary tour in 2019.
A statement from the current UB40 line up on Twitter said: "RIP Astro.
"We have heard tonight, the sad news that ex-member of UB40, Terence Wilson, better known as Astro, has passed away after a short illness. Our sincere condolences to his family."
In total, UB40 have recorded 39 UK top 40 singles and 28 top 40 albums, with Astro singing lead vocals on the hit 'Rat In Mi Kitchen' which reached number 12 in 1987.
The original line-up played together for three decades before Ali Campbell left in 2008.
- additional reporting BBC
