Milne was sacked by the Tigers during the 2018 season after testing positive to an illicit substance, but reached out to Warriors coach Stephen Kearney via a handwritten letter asking for a lifeline.
"I told him I'm not a drug addict," Milne told the Telegraph.
"I wrote to him — spelling errors and all — telling him that I wanted to play in the NRL again. That I owned up to my errors and I was on the right track. I knew I could offer something to the club."
The Telegraph also reports that Warriors skipper Roger Tuivasa-Sheck and recruitment manager Peter O'Sullivan, who originally recruited Mile to the Roosters, both reached out to the troubled 23-year old to offer their support.
"I don't have a drug problem," Milne said.
"I made a mistake. A really costly one and I embarrassed myself and my family. I felt so much embarrassment.
"It was my fault though and I can't blame anyone else. I did this to me. But I have learnt so much. I've grown up. I had a really good job and I lost it all.
"I thought my NRL career was done and people would just remember as a guy who had a drug problem. I want to use this to help people. Only now am I comfortable speaking about what I did.
"Alcohol was a factor and I've been off it for months. I've made a promise to myself not to drink the entire pre-season."
Milne will arrive in New Zealand today and begin pre-season training with his new club tomorrow.