The former heavyweight champion made the startling revelation while at a press conference to promote ESPN's Friday Night Fights at the Turning Stone Resort in Verona, New York on Friday.
'I'm a bad guy sometimes,' he said. 'I did a lot of bad things, and I want to be forgiven... I wanna change my life, I wanna live a different life now. I wanna live my sober life.
'I don't wanna die. I’m on the verge of dying, because I’m a vicious alcoholic.'
After realising what he had shared, he paused before adding that he has not consumed alcohol or drugs in six days, which he called 'a miracle'.
'I've been lying to everybody else that think I was sober, but I'm not,' he admitted. 'This is my sixth day. I'm never gonna use again.'
Tyson's struggle with alcohol and drugs has been well documented; he has been in and out of rehab three times.
He has also admitted that around five years ago he was contemplating suicide and overdosing - just before his four-year-old daughter Exodus died on May 26, 2009.
'I didn't think I'd be here much longer,' Tyson said. 'I was planning on killing myself. I was overdosing every night. I couldn't believe it - that I was waking up. Living life is different for me.
'I had to change my life. It's been hell, but I'm happy to be alive.'
In an interview with Nightline in July 2012, Tyson claimed he had been sober for three years.
'I'm just constantly working on turning. It doesn’t happen overnight,' Tyson said in the interview.
'I may have a good few years in me but it's still not out of me. You still have to work consistently. Every moment of the day you have to work because your demons always - that's who you are.'
His comments on Friday came as he spoke about trying to make amends with Teddy Atlas, his former trainer whom he famously fell out with in the early 1980s.
Tyson said he knew Atlas was going to be at the Fight Night Fights event and described how he initially struggled with how he would handle seeing him again.
'I didn't have a good thought in mind about that at first, because I'm negative and I'm dark,' Tyson said. 'And I wanna do bad stuff. I wanna hang out in this neighbourhood alone [pointing to his head].
'That's dangerous to hang out in this neighbourhood alone up here, right? It wants to kill everything. It wants to kill me, too.'
He added of Atlas: 'He has to know this is sincere. I don't wanna fight you no more. I was wrong. I'm sorry.'
Last month, Tyson announced he's teaming with director Spike Lee to bring Tyson's one-man Broadway stage show, Mike Tyson: Undisputed Truth, to HBO later this year.
Tyson's wife, Kiki, wrote the script for the stage show, which toured the country earlier this year.
Tyson said it reflects his life's journey from Brooklyn street tough guy to happily married father, and credits his wife for his foray into promoting.
'I'm incredibly grateful to HBO for partnering with me and for believing in my story,' Tyson said. 'It is an honour and a privilege to be working with them to bring my one-man show, 'Undisputed Truth,' to live on the television screen.'