The new track is the first single taken from a new Greatest Hits collection from the Irish group, to be released on November 21.
'Lighthouse' is co-written by John Shanks and Take That's Gary Barlow. Westlife's Mark Feehily and Nicky Byrne explained that the group are excited to have worked with "the competition".
"'Lighthouse' was written for us by Gary with John Shanks," Feehily told the Daily Star. "They wrote 'Patience' for Take That so we're confident we have a great team behind our new song."
Byrne explained: "Some people might think Gary would be seen as the competition but we don't at all. It's kind of cool he's written for us."
Feehily added: "I love the idea of Gary writing for us and throwing all the rules out the window."
Westlife's new collection will go head-to-head in the album chart against fellow boyband One Direction when they are released in November.
Watch the video for Westlife's 'My Love' below: