She said: "I've had a wonderful time in the sport.
"I'm really proud of what I have achieved but I know in my heart that now is the time to go.
"I have put my life and soul into my sport and I've had some great highs because of it.
"Staying on for the London Olympic Games would have been a big attraction, but I hope to be able to stay in the sport and contribute in other ways."
GB Rowing performance director David Tanner paid tribute to Winckless.
He said: "Sarah has played a huge part in the emergence of GB Women's rowing as a world force in the past 10 years and can look back with great pride on her Olympic medal in Athens [in 2004] and two world titles in 2005 and 2006."
Winckless took up rowing at Cambridge University before making her GB senior debut at the World Championships in a women's eight in 1998.
In 2004, Winckless teamed up in a double scull with Elise Laverick and the duo produced a strong World Cup season before going on to win Olympic bronze in Athens.
That was followed by a move into the top boat, the quad, where she became double world champion in 2005 and 2006.
Winckless, who has worked part-time throughout much of her rowing career, has been a strong squad member often representing the needs of her fellow athletes as an athletes' representative.
She was part of the British Olympic Association committee which designed the 2008 Olympic kit to be more athlete friendly.
Winckless has also been a charity campaigner to raise awareness and funds for those affected by Huntington's Disease, a disease for which she carries the mutant gene.
