The Jamaican completed the triple-triple at Rio 2016, taking his tally of Olympic gold medals to nine.
Along with his Games success, he is an 11-time world champion and world-record holder in the 100 metres, 200m and 4x100m.
Asked if he was now the greatest, Bolt replied: "Yes, I definitely think so. I've really put my all into it.
"I really worked hard to accomplish the greatness that I have done so I am really proud of myself and accomplishments that I have done so I am really happy about it."