The 30-year-old won Olympic gold in the heptathlon at London 2012 and silver at Rio 2016, and is a two-time world champion.
Ennis-Hill released a statement on her Instagram account saying it was “one of the toughest decisions” she has faced but “retiring now is right”.
It read: “”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 x”