"My body is tired, and it feels sad that this is over now," she told SVT.
"This is a part of life I'm leaving behind me now. I'm unbelievably happy and proud to have been part of it."
Kluft, 29, dominated the heptathlon from 2002 to 2007, winning Olympic gold in 2004 and three world titles. She then swtiched to the long jump.