Up until April 2015, Klitschko had only lost three of his 67 professional fights, but he was then beaten by two British fighters - Tyson Fury and Anthony Joshua.
His final defeat to Joshua at Wembley was considered by many as a classic heavyweight title fight, with both men sent to the canvas during the bout.
However, in the 11th round there was no way back for Klitschko as Joshua unleashed a barrage of punches that left the Ukrainian beaten.
There was talk of a rematch but Klitschko chose to hang up his gloves rather than fight on, opting to focus on other interests.
Despite finishing up with two successive defeats, the 41-year-old has no regrets and looks back fondly on a hugely successful career in the ring.
"It wasn't an easy decision to pull the plug after 27 years," he told DAZN. "You say 'oh sure, I'll do that easily', but it's not true, because you really have to pull yourself out of it.
"It's not easy and I understand my fellow athletes who weren't able to do it when they wanted to and had to keep going.
"After 27 years, I can say that I ended my career successfully, even if I lost my last fight. I've never won so much with a defeat before. I can say that I ended my career successfully.
"There were a lot of highlights, which are often talked about. I enjoyed both the wins and the losses. The losses helped me, that's when you truly get to know yourself.
"You learn to work with yourself and explore new sides of yourself. It was a great time to be involved in sport, including for my future, because life after sport will be just as long.
"The sport taught me so much, like no university in the world ever could. I am glad I took this path in my life and that I became the athlete so I could explore the world on my own."
Photo Getty Images. Caption: Anthony Joshua and Wladimir Klitschko