The singer, who is now expecting a second child with wife Giovanna Fletcher, said having a child gave him a sense of stability in life.
Fletcher spent time in rehab after being diagnosed with depression five years ago and said he has now stopped taking his medication.
He told Mirror's 3am: "Having a kid has really helped me in my life. It gives you a sense of needing to be stable.
"It’s not about you any more, it’s about this child that you’ve decided to bring into the world."
The 30-year-old star said when you becoming a parent, your priorities completely shift.
He added: "You don’t have any choice but to cope with life because you’re doing it for someone else. I was very ready for that before Buzz was born."
Fletcher has been open about his depression, admitting to OK! Magazine in 2013 there were moments he thought "I can't do this anymore".
He said: "But I guess you always see sense just at the right time, or just when you think you’ve had enough, something happens and there’s some sort of light at the end of the tunnel."
In McFly's autobiography, Unsaid Things... Our Story in 2012, the dad-of-one was open about being diagnosed with depression, seeing a psychologist and psychiatrist, and starting sleep therapy.
He has since worked with mental health charity Mind to help raise awareness of depression.
Fletcher and his wife Giovanna revealed in September they were expecting their second child together with a videogame creation announcement.
The singer can be found frequently posting updates on his wife's growing bump on Instagram.
For more advice on depression and other mental health issues, visit Mind.