After taking silver at the Rio Olympics in August, the 30-year Ennis-Hill dropped a retirement hint.
"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," she said on Instagram.
"I've always said I want to leave my sport on a high and have no regrets and I can truly say that," added the 30-year-old Briton.