Mark Feehily of the band - also comprised of Shane Filan, Kian Egan an Nicky Byrne - has revealed as well as the lead single 'Hello My Love', the 28-year-old pop star also worked with producer Steve Mac on five of the other tracks on 'Spectrum'.
Speaking to OfficialCharts.com, Mark revealed: "He's done six songs for the album.
"So effectively half the album.
"One day Ed went in the studio and said 'I just want to write Westlife songs'. It's been a truly organic coupling."
The 'What About Now' hitmakers' first new studio record since 2010's 'Gravity' will drop on September 6, and they think the LP's title perfectly sums up their newfound energy.
The group recently said: "The title 'Spectrum' came from us talking about how we feel younger, happier and more energetic than we ever have in our career.
"'Spectrum' is a title that represents the various different shades and colours of our personalities, vocals and general perspectives that all blend together in a unique way to create Westlife.
"It's also a word that represents the various shades and colours in the band, meaning it's the perfect metaphor for our different points of view and perspectives but together, they somehow join to work perfectly."
The band have teamed up with James Bay for a collaboration on the album.
And they feel the LP displays "the very best version of Westlife possible".
They added: "We're all driven by trying to create the best album of our careers. Our fans deserve the very best version of Westlife possible and with this album we feel that we've achieved that.
"The album has everything that we love in music, heartfelt emotional songs and also great uptempos that are designed for our stadium performances.
"We couldn't be happier with how the last few months in the studio have gone and we cannot wait for our fans to hear the end results."