French also won five world championship medals and six European gold medals in her career, and claimed the World Cup title during a dominant 2021 in which she was ranked number one in the world.
The 33-year-old returned to the sport after 18 months away last summer to compete in Paris, but sickness hampered her chances of winning another medal and she withdrew from competition on the final day.
In a post on Instagram, external, French said she leaves the sport “with a heart full of happiness and a head full of wonderful memories”.
She added: “There were many highs and lows, but it’s been an amazing adventure and truth be told, I wouldn’t change a thing.”
French, from Kent but now based in Wiltshire, has been involved in the sport since joining the British Pathway Programme in 2007.
In 2010, she was part of the team that won the junior world title before winning a first senior world gold medal in the team event in Taiwan in 2013.
French finished fifth in Rio in 2016 at her first Olympic Games before storming to the title in Tokyo five years later.
She swam a personal best in the 200m freestyle and finished more than 15 seconds ahead in the laser run to set a new Olympic record for the highest points total in the event.
French took a break from the sport after winning gold in 2021, only competing twice the following year, before stepping back again in 2023 as she did “not want to regret” not trying out for the Paris Games last summer.
“From a performance side Kate dominated the sport, and from a personal side she continues to inspire in the way she did it,” said Jamie Cooke, head of performance at Pentathlon GB.
Modern pentathlon is undergoing a significant overhaul before the next Games in Los Angeles in 2028, with showjumping removed from the five-event sport to be replaced by a Ninja Warrior-style obstacle course.
