Smith, who came out gay last year, has taken a vow to stand up for gay kids, reported People magazine.
"At the beginning of last year I wasn't talking about my sexuality as much. But I've sold loads of records now and I have a voice. I can speak about this from a position of power, compared to two years ago. It wouldn't have gone anywhere."
Smith says he was getting bullied even before coming out as gay at 11 years old. He said that as a child, boys would come up to him and ask if he was gay, and when he replied "no," it would rile them up even more.
The abuse turned physical when he moved to London, he said he got punched in the neck while walking back from work.
"I've been through stuff, but I'm lucky because none of it has damaged me. My parents were amazing, but there was only so much advice they could give," he said.