The winner was decided at the finishing line. Italy overtook Britain to win by 0.01 second at 37.50 seconds ahead of Britain's 37.51.
Canada, anchored by men's 200m gold medallist Andre de Grasse, finished 3rd in 37.70.
Led by China's star sprinter Su Bingtian, the Chinese team finished fourth again with 37.79 after the final in Rio 2016.