The Australian tennis entertainer has opened up about one of the "darkest periods" in his life around the time of the 2019 Australian Open.

The 26-year-old said he was struggling so much he turned to self-harming.

"Most would assume I was doing OK mentally or enjoying my life ... it was one of my darkest periods," Kyrgios wrote on Instagram, accompanied by a picture of him at training.

"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."

Kyrgios, who went on an extraordinary run at the Australian Open with Thanasi Kokkinakis to claim an unlikely doubles title last month, said he was now in a much better place in his life.

"'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."

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Australian Associated Press