Jess confirmed the news via social media, telling fans she wanted to leave her sport "on a high" and with "no regrets."
The mum-of-one shared a collage of photos that pinpointed moments from her sporting career on Instagram and added the caption: "Amazing memories... 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."
Jess's announcement comes after she hinted at retirement following her success at the Rio Olympics this summer. After finished second in the heptathlon and gaining a silver medal, the 30-year-old was visibly choked during interviews that followed the event. She had told the BBC: "I've got to go away now and make a decision as to what I do. I don't want to cry on TV but, yeah, these years have been amazing so I'm really proud."
When asked if Rio could be the last heptathlon she competes in, Jess, 30, replied: "Possibly, yes."
Jess' decision comes over a year after she returned to athletics, following the birth of her son Reggie in 2014. Reggie is her first child with husband Andy Hill. The couple married in May 2013, and welcomed Reggie in July the following year.
Throughout her athletics career, Jess has won two World Championships, as well as an Olympic Gold from her efforts at London 2012.
Since announcing news of her retirement, Jess has received a slew of support from fans. One commented: "Such an inspiration in the sport, one of my favourite athlete and love seeing her compete,congratulations on your fabulous career Jess." Another added: "Always a champion."
Over on Twitter, some suggested that we may now get to see Jess on our screens on this year's I'm A Celebrity. One user predicted: "Great Athlete in Jessica Ennis-Hill has retired,cheers for the greatness.I now look forward to seeing you on @imacelebrity #Ennishill."
She'd definitely make a great contender, wouldn't she?!
Jessica Ennis-Hill is not just a Sheffield legend, but a UK legend. She will be much missed by the athletics world.— Adam Allcroft (@Adam_Allcroft) October 13, 2016
I'm absolutely heartbroken that Jessica Ennis is retiring! We love you Jess— Keeks (@Keaunaboo_) October 13, 2016
Fantastic Athlete#RoleModel enjoy retirement Jessica Ennis!!— Kerry Aryeetey-H (@jazz2nov) October 13, 2016
Jessica Ennis-Hill though. She is a great. No question.— Poor Little Greeny (@DarkLordCrimson) October 13, 2016
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