In an unexpected, but dramatic fashion on Sunday after a first lap collision with title rival Sebastian Vettel, Lewis finished ninth in the Mexican Grand Prix.
The 32-year-old Briton, who would have needed to finish in the top five to be sure of the title if Vettel had won the race, battled from last position in his Mercedes after suffering a puncture that needed an opening lap pit-stop as Dutchman Max Verstappen won the race for Red Bull.
Vettel, already a four-time champion, came home fourth for Ferrari after driving through the field from 19th following his part in the early crash with Hamilton. He also pitted for a new front wing.
Hamilton's title triumph made him the first Briton to be a four-time champion, elevating him clear of Jackie Stewart, and alongside Vettel and Frenchman Alain Prost.
Only German Michael Schumacher with seven titles and Argentine Juan-Manuel Fangio on five have claimed more championships than the Englishman.