The injury-plagued 25-year-old, who has not competed since an unsuccessful 2012 London Games, has had three shoulder operations.
"Coming off the Games, I really didn't want to make a rash decision on my career and if I was going to keep swimming or not because I was still too emotional," Rice said.
"I knew I had to take the time for myself to get to the point where I knew 100 percent what I wanted to do."
The Queenslander clinched three gold medals and three world records in the 200m and 400m individual medleys and the 4x200m freestyle at the 2008 Olympics.
"To win one Olympic gold medal is hard enough, but to win three at the same Games is a fantastic achievement and something that will forever be remembered within the sporting fabric of this nation," he said.