The former Olympic champion was knocked out in humiliating fashion by American Deontay Wilder in Sheffield on Saturday in a hopelessly one-sided 70-second fight.
After the crushing defeat Harrison admitted that it could be the end for his professional career, and it was subsequently confirmed on Wednesday.
"There are only so many times you can fall before it becomes foolhardy to continue," the 41-year-old said in a statement. "I've fallen a lot, but winning the heavyweight title was a destination I really wanted to get to.
"Coming back from adversity has been synonymous with my life. I've done well to turn my life around, but sadly my dream to be a legitimate world champion will be unrealised.
"Our life is a one time deal, no rehearsals, so the regrets I have, I live with and accept...I got focused a little late in life, so I've had to learn some tough lessons along the way."
Harrison lost seven fights out of 38 as a professional since winning the Olympic heavyweight gold medal in 2000.