Kewell will bring his career to an end against Western Sydney Wanderers on April 12 in the final game of Melbourne Heart's campaign.
"It's been tough," the 35-year-old revealed in a statement. "I've talked to a lot of people recently and it's hard because it's the only sport I've ever known. I started when I was four and started professionally when I was 17 and had a career of 18 years.
"It's a life I've already lived and now I get a chance to live another one."