Hamilton, who won the world title for the third year in a row, surpassed the legendary five-time champion, Argentina's Juan Manuel Fangio, and is now behind only to the seven-time champion, Germany's Michael Schumacher.
"Still we rise guys, still we rise. Thank you so much, guys - we did an incredible job... I can't believe it," Hamilton said after finish.
Hamilton finished the US Grand Prix second, behind his teammate Valtteri Bottas of Finland, while Dutch racer Max Verstappen was third.
Hamilton won five out of six world titles (2014, 2015, 2017, 2018 and 2019) with Mercedes in the so-called hybrid era. He won his first championship as a pilot of McLaren back in 2008.