The Irish band parted ways in 2012 after a phenomenal career that saw them receive over a billion views on YouTube and sell over 55 million records worldwide.
Now, Nicky Byrne, Kian Egan, Markus Feehily and Shane Filan are said to be on the verge of announcing a full-time comeback.
“Westlife have really been pulling out all the stops for their big comeback and were desperate to get Ed on board,” a source told The Sun.
“It took quite some time to pull together and has been done totally behind closed doors, but he has finally given them the right record to make it happen.”
“Having Ed involved is a huge coup,” the insider added. “They think he will give them a contemporary edge for their reunion.
“They have already recorded the song and are delighted with the results.
“They’re just pulling together the final promo details including a video before they unveil it. It’s going to be huge.”
Brian McFadden left the group in 2004 and is not thought to be part of the reunion plans.
Last year he told Express.co.uk he did not expect to be part of any new projects, as the group neared their 20th anniversary.
“I don’t know what they’re gonna do, there’s no talks of the five of us doing anything,” he told us.
“There might be talks for the four of them doing something; I don’t know what they’re doing.
“But at the moment, it’s just going to be an anniversary. We’ll probably tweet each-other going, ‘happy anniversary, 20 years…’”.
Westlife released ten studio albums between 1999 and 2010, all of which reached the Top 3 on the UK charts.
They also scored 14 number one singles, including their first six consecutive releases.
They’ve all attempted solo excursions: Byrne released his album Sunlight in 2016, but failed to crack the Top 100 in the UK (though he did reach the Top 10 in Ireland). Egan’s effort Home, released in 2014, hit No2 in Ireland and No9 in the UK.
Feehily managed No25 with Fire in 2015, and No2 in Ireland; while Filan has released three solo records between 2013 and 2017 – all of them reaching the Top 15.