Looking back on a career of 'amazing memories', she said: "From my first world title in Berlin 2009 to Rio 2016 I'm so fortunate to have had such an amazing career within the sport I love and this has been one of the toughest decisions I've had to make.
"But I know that retiring now is right. I've always said I want to leave my sport on a high and have no regrets and I can truly say that.
"I want to thank my family and incredible team who have spent so much of their time supporting me and enabling me to achieve my dreams. Also a huge thank you to all those people who have supported and followed my career over the years."
People have been sending messages of support to the Olympian and her family. On Twitter, David Richmond said: "You've been an inspiration and a true ambassador for your sport. Good luck."
Kevin Powell said: "Thanks for sharing your dreams and inspiring others."
And Richard May said: "Good luck in retirement - and thanks for the great memories."
Here are 6 things you might not know about Jessica:
Ennis-Hill has been coached by Toni Minichiello since she was 13.
Ennis-Hill graduated with a psychology degree from the University of Sheffield in 2007. In 2010 Ennis was awarded an Honorary degree from the University of Sheffield for her contribution to sport.
Born and bred in Sheffield, she still lives in the city with husband - childhood sweetheart Andy - son Reggie and a chocolate labrador, Myla.
Ennis-Hill is a fan of Star Wars and has compared herself to Rey, the female lead protagonist in recently released The Force Awakens.
When coming through the ranks, Olympic bronze medallist Kelly Sotherton gave her the nickname ‘tadpole’ because of her diminutive size and age. She is now five feet five inches tall.
To celebrate Ennis-Hill’s Olympic success, League One side Sheffield United renamed one of the Bramall Lane stands after her. It was changed to the Redbrik Estate Agency Stand last June.