In a lengthy statement on Instagram, Kyrgios said the last few years of injuries had taken “a huge toll on me, both mentally and physically”.
“My body hasn’t been able to do what my mind expects it to do,” he wrote.
“Coming to terms with being near the end of my career has been harder than I ever imagined.
“None of that excuses what I did.”
Kyrgios said he would be stepping away from social media and public life for the next 28 days to “focus on getting myself right”.
Cocaine is classified as a stimulant and substance of abuse on the World Anti-Doping Agency’s prohibited list.
Reduced sanctions apply for athletes who test positive for the substance out of competition.
However, Kyrgios’ sample was submitted during a tournament in which he played singles, ultimately losing in the first round to Adam Walton.
“I’m sorry to my fans, my family, my sponsors and everyone close to me,” Kyrgios added.
“Above all, I’m sorry to the kids who follow me. I know the example this sets and I’m deeply disappointed in myself.”
