"I'm turning 40 next year and I guess I'm moving into the age where men's health issues become more common. You do become more aware of problems."
Barker is married to former New Zealand hockey representative Mandy Smith. The couple have three daughters, Mia, Olivia and Isla and a son, Matteo.
For his father, Ray - founder of the men's clothing label Barkers - getting behind the cause also came about after a close friend was diagnosed with prostate cancer.
" He was a person who had just recently retired and within a very short space of time was diagnosed with prostate cancer.
"Being close to them, we've been close to his treatment process and recovery from there.
"But now, fortunately, I'm pleased to say he's in great health ... and he's getting great reports. So it's great to see."
Mr Barker admitted it felt a little odd having a moustache, his first since the 1970s.
"Now that I'm sort of quite grey, the mo's turning out the same colour."
Asked if the mo was back on trend, he said: "It's hard to say if a mo's fashionable or not. It suits different people ... but we're doing it for a different reason, for a good cause. Who knows, the grey mo might become the new trend."
To donate or register to Movember visit: www.nz.movember.com.