The former Westlife singer, who recently wed DJ Vogue Williams, was married to ex-Atomic Kitten singer Kerry Katona from 2002 to 2004, and was engaged to Australian singer Delta Goodrem in 2011.
McFadden told Hello: "For me this is my first time getting married.
"This is me getting married for the rest of my life - and a completely different life."
He added: "I was 18 or 19 when I got married the first time. I was in Westlife. I had no idea what I was doing. It wasn't till I was 30 that I turned into an adult."
McFadden is reportedly keen to start a family with his new wife, but Williams is rumoured to want to wait a while and enjoy married life first.