Crouser took the lead all the way, and threw 23.30 metres in his sixth attempt, refreshing the Olympic record.
Crouser's compatriot Joe Kovacs bagged the silver with 22.65m, while Tomas Walsh of New Zealand took bronze with 22.47 metres.
Pedro Pichardo of Portugal took an outright victory in men's triple jump while China took a historical silver on Thursday.
Pichardo only succeeded in his first three attempts -- 17.61 metres in the first two and 17.98 in the third attempt -- but it was enough to secure the gold medal.
China improved from the bronze medal in Rio 2016 as Zhu Yaming took silver with a personal best of 17.57 metres, the best result for China at the Olympic Games.
Hugues Fabrice Zango won bronze, the first-ever Olympic medal for Burkina Faso.
Jamaican hurdler Hansle Parchment took a surprising victory in the men's 110m hurdles final on Thursday.
Race favourite Grant Holloway of USA came out quickly but Parchment overtook him through the final hurdle and crossed the line first with 13.04 seconds.
Holloway took silver with 13.09 and Ronald Levy of Jamaica won bronze with 13.10.