29yrs old Bolt had won the 100m and 200m in Rio and is the only man to win all 3 sprint events at 3 Games. He paired with Asafa Powell, Yohan Blake, Nickel Ashmeade to finish in 37.27 seconds.
Japan won a surprise silver and the USA were disqualified to hand Canada bronze and lift Britain up to fifth.
"There you go. I'm the greatest," Bolt said as he ends one of the most astonishing Olympic careers.