In an Instagram post, Kyrgios shared a picture from the 2019 edition of the Australian Open and highlighted his issues surrounding mental health at the time.
The 26-year-old also urged people in similar situations to find help and support.
He wrote: "This was me 3 years ago at the Australian Open. Most would assume I was doing ok mentally or enjoying my life… it was one of my darkest periods.
"If you look closely, on my right arm you can see my self harm. I was having suicidal thoughts and was literally struggling to get out of bed, let alone play in front of millions. I was lonely, depressed, negative, abusing alcohol, drugs, pushed away family & friends.
"I felt as if I couldn't talk or trust anyone. This was a result of not opening up and refusing to lean on my loved ones and simply just push myself little by little to be positive.
"I know that day to day life can seem extremely exhausting, impossible at times. I understand that you feel if you open up it may make you feel weak, or scared. I'm telling you right now, it's OK, you are not alone.
"I've been through those times when it seemed as if those positive energetic vibes were never ever going to be reality. Please, don't feel as if you are alone, if you feel as if you can't talk to anyone, I'm here, reach out.
"I'm proud to say I've completely turned myself around and have a completely different outlook on everything, I don't take one moment for granted. I want you to be able to reach your full potential and smile. This life is beautiful."
Now ranked down at 137, Kyrgios has played very sparingly on the ATP Tour over the past couple of years but was this week given a wild card for next month's Masters tournament in Miami.
The Australian tennis star won his first grand slam title in men's doubles at the Australian Open last month with close friend Thanasi Kokkinakis.