THEY sold more than 50 million albums, racked up 14 UK number ones and toured the world.
The 34-year-old, pictured right, has revealed how they all made poor business decisions and handled finances badly starting out.
"We have all lost money. We were all very foolish with money in the early days, we all bought cars and watches – the silly things.
"I don't think any of us were lucky," said Byrne.
The biggest financial meltdown was suffered by Shane Filan, who was declared bankrupt in a UK court earlier this year for outstanding debts of up to €23m.
However, his bandmate revealed how their income had dropped off by the end of their 14-year career.
"We did very well out of Westlife but everybody lives and spends," he said.
"In the early days we earned great money, and in the latter days it was all gone.
"We all looked after it as best we could but none of us are absolutely minted," he added.
The father of two revealed how he found life after Westlife "very strange", but said 'Strictly Come Dancing' helped him move on.
"Having been in Westlife, I thought we had got to a level where we had done it all. "But no, the fanbase for 'Strictly' is phenomenal. This was a different league and a different ballgame. Everywhere you went, people wanted to talk to you. I found it overwhelming," said Byrne.
Voted off 'Strictly' earlier this month, the former popstar said he now wants to move into TV presenting.
"At this time of the year we would usually be very busy promoting an album. I'm not the sort of person who likes to sit around and do nothing."
Byrne and dance partner Karen Hauer will feature with other runner-up couples in the live finals of 'Strictly Come Dancing' this Saturday on BBC1.