Starting fifth on the grid on Sunday, Hamilton worked his way up to third on lap one and assumed the lead as his rivals pitted for tyres, while the Briton elected to stay out for longer on a different strategy, reports Xinhua news agency.
Nursing his tyres well, the Briton led much of the race before ultimately giving best to teammate Valtteri Bottas, who used his fresher rubber to catch and pass Hamilton with just four laps to go.
However, the result was largely academic, as Hamilton had only needed an eighth place finish in Austin to be sure of his sixth world title, and the 34-year-old now has an unassailable points total of 381 with just two races left this year.
Hamilton, who started his racing career in the 2001 British Formula Renault Winter Series, now sits alone in second place on Formula 1's all-time list of title winners, with only seven-time champion Michael Schumacher ahead of him.
With 83 race wins in total, Hamilton is also within striking distance of Schumacher's all-time record of 91, and stands a good chance of surpassing the German in 2020 if his Mercedes team can maintain the form that has seen them win both drivers' and constructors' titles for the past six seasons.
Elsewhere in Sunday's race, Red Bull's Max Verstappen finished third behind Bottas and Hamilton, while Charles Leclerc took a distant fourth place on a very disappointing day for Ferrari, whose race pace was an average of one second per lap slower than the Mercedes and Red Bulls.
Verstappen's teammate Alex Albon recovered from contact and an early pit stop on lap one to finish fifth, ahead of Daniel Ricciardo in a fine sixth place.
The two McLarens were seventh and eighth, with Lando Norris edging Carlos Sainz, followed by Ricciardo's teammate Nico Hulkenberg in ninth and the Racing Point of Sergio Perez rounding out the points paying positions in tenth.
The next round of the 2019 Formula 1 season is the Brazilian Grand Prix in Sao Paulo on November 17.
( With inputs from IANS )