The boyband will release 'Lighthouse' on November 13, with their Greatest Hits compilation to follow a week later on November 21.
The track was co-written by Take That's Gary Barlow and John Shanks, while the accompanying video was filmed in South Africa last month.
'Lighthouse' is Westlife's 31st single since their chart-topping debut 'Swear It Again' in 1999.
The band have sold over 11 million albums and 6 million singles in the UK to date, with further sales accumulated across Europe and Australia.
The group will reportedly take a break of up to two years following the release of Westlife: The Greatest Hits in November.
> Westlife's new single 'Lighthouse': First listen
Listen to a teaser of Westlife's 'Lighthouse' below: