The singer reached the final of the BBC One talent show on Saturday, ahead of fellow Team will.i.am member Jaz Ellington.
He explained that he would often damage his body with his alcohol intake, but that the show has helped improve his life.
"I've gone from drinking myself into a coma into the happiest man alive," he told The Sun.
He added that hearing that he had made the final has given him fresh hope that he will not suffer the same kind of fate of his close friend Amy Winehouse.
"I welled up. Just to know that the public had picked me to be in the final was the most amazing feeling in the world.
"I feel like I'm exaggerating when I talk about it but it's changed my life. It could have been so much different."
Talking about his past health issues, he said: "It's crazy to think that not that long ago I was so depressed I got to a point where I wouldn't even drink to be out of it — I'd drink to not be awake. I couldn't be awake. I couldn't deal with my own head.
"At any given moment I would just drink myself unconscious with booze and sleeping tablets. I didn't want to kill myself but it could have happened so easily."
He added that he normally would not have applied for a show such as The Voice UK, but eventually found the drive to do so.
"I'd never in a million years normally go in for this. I always saw people in X Factor and thought, 'How do they do that? It looks hard'.
"You have to put yourself out there and have people judge you. I used to applaud them but couldn't do it myself.
"But once Amy wasn't here there was a part of me that thought, 'Life is too short. Anything goes now'. Instead of constantly procrastinating — I'm a massive over-thinker — I thought, 'Right, let's just do this'."
Tyler James released a solo debut album The Unlikely Lad in 2005, but it failed to chart in the UK.
He will now face off against Leanne Mitchell (Team Tom Jones), Vince Kidd (Team Jessie J) and Bo Bruce (Team Danny O'Donoghue).
The finalists will compete in next week's final on Saturday, June 3 at 7.20pm on BBC One.