The 27-year-old claimed women's lightweight double sculls gold with Katherine Copeland at the London 2012 Olympics last summer as Britain's rowers dominated on Dorney Lake.
Hosking's gold was one of four won by Team GB as they topped the rowing medal table, with two silvers and three bronzes also collected, and came at both her and Copeland's maiden Olympics.
Almost 12 months on from the feat in which time Hosking has reflected on her next move, she has decided to call time on her career during which she made her senior world debut in 2006 at Dorney.
Hosking claimed bronze on that occasion, the first of three throughout her career at the World Championships with silver following in 2007, and insists the revelation of retirement is purely positive.
"After the Olympics I knew it had to take some time out from rowing to gain some perspective on what we had achieved and to explore whether or not I had the same drive to continue training and competing at the highest level," said Hosking.
"After much thought I have decided to retire. For me this is in no way a negative decision but recognition of a feeling of completion as an athlete. I feel that I put all of myself into the sport over the past 12 years and I am very proud of the athlete I became and the results that I achieved.
"I would like to thank everyone who has helped me in my career, to whom I owe so much of my success; my coach Paul Reedy for his inspiration, selfless dedication to our cause and unwavering belief and confidence in me.
"Everyone that I have raced with over the years, especially my doubles partners Hester Goodsell and Kat Copeland, the memories you have given me over the years beneath all the TV footage, I will always cherish; also my family who have been my absolute rock through all of the highs and lows."
Hosking will now do a law conversion, starting in September, before taking up a training contract with Freshfields and she can't wait to get her new career going.
"I am really excited by this new challenge," she added. "Law has always appealed to me and I really enjoyed the buzz of the environment and being surrounded by incredibly motivated people."