The boyband, who will embark on their 'Farewell Tour' of the UK and Ireland in May, confirmed that girl group Vanquish will open their shows.
Speaking about their appointment, the group said: "To be supporting Westlife on their final UK arena tour is an amazing feeling!
"We feel honoured to be part of this. We are going to bring fun, excitement and some powerful Vanquish pop songs to the tour. Can't wait to get on stage!"
The four-piece have been working with producers Rob Davis and Jorgen Elofsson for their debut album.
Between them, the producers have previously worked with the likes of Britney Spears, Kelly Clarkson, Jennifer Lopez and Kylie Minogue.
Vanquish's debut single 'The Harder You Love' will be released in April.
Watch the music video for Vanquish's 'The Harder You Love' below: