Missy Franklin -- the Olympic prodigy who won 4 gold medals as a 17-year-old in the London Games -- has announced she's putting an end to her swimming career at just 23 years old.
The first American woman ever to earn 4 golds in one Olympics in any sport announced in a statement on ESPN on Wednesday that shoulder injuries are putting an end to her career.
"It took me a long time to say the words, 'I am retiring,'" Franklin wrote ... "A long, long time. But now I'm ready. I'm ready to not be in pain every day."
"I'm ready to become a wife, one day a mother. I'm ready to continue growing each and every day to be the best person and role model I can be. I'm ready for the rest of my life."
Franklin was an absolute monster in the 2012 Olympics ... smashing world records and boat racing the competition.
But, Missy is perhaps MOST famous for turning down all the cash that coulda come from her success in those Games ... 'cause she opted to not go pro and instead swim at Cal Berkeley.
Franklin disappointed years later in the 2016 Olympics in Rio ... failing to earn medals in her individual's events -- and later revealing she battled injuries, depression, insomnia and anxiety during those Games.
"This is by no means the end," Franklin wrote of her retirement.
"Rather, I choose to look at this as a new beginning. Swimming has been, and always will be, a big part of my life and I absolutely plan to stay involved in what I feel is the best sport in the world, just in a different way."