The popstar - whose boy band at the height of their fame in the nineties, sold 25 million records worldwide - said his rebellious character was enhanced when he joined the group in 1993.
"I was the extreme guy who stuck out like a sore thumb. It was a squeaky-clean kind of band and there's me with nose rings, tattoos and a bit of a swagger.
"I felt I had to play up to all that because that was my identity in the group."
By 2000, when lead singer Ronan Keating had quit to pursue a solo career and the band took a break, the Donaghmede-born musician said he was in a "dark place and lost".
"I dabbled in the occult and was dancing with the devil, and doing all sorts of negative things looking for escape from myself. I'd lost respect for myself."
Now happily married to former backing singer Sheena White - the couple have two daughters, Billie Rae, eight and Marley Mae, four - Lynch says he doesn't regret his past as it made him the man he is today.
The singer whose Twitter bio begins with the word Jesus said: "I was very immature and selfish during that time, but I worked my way through that, found my Christian faith and understand the world and myself nowadays.
"I've never regarded myself as a celebrity. I'm just a guy who loves racing cars, working to look after my family, and every now and then I'm in a band called Boyzone."
