"It is my best season in MotoGP. I want to say thanks to all my team," Marquez said after the race.
The 26-year-old Spaniard has claimed world titles in 2013, 2014, 2016, 2017, 2018 and 2019, all of them with Honda, Efe news reported.
It became Marquez's eighth world title overall, having been crowned the world champion in Moto2 and 125cc once apiece in 2012 (Suter team) and 2010 (Derbi team).
The rider hailed his team members' consistency, competitive mentality and the manner in which they worked on the weak points throughout the season.
"They're able to do it and this is one of the most important things," Marquez said.
Following the race at the Buriram International Circuit, King Felipe VI of Spain tweeted a congratulatory message for Marquez.
"When a great champion rides at full speed on the road to become a legend. Giant Marc Marquez," a post on the Spanish Royals' official Twitter account said.
After Marquez and Quartararo, who had a thrilling race on Sunday, Spaniard Maverick Vinales of Monster Energy Yamaha MotoGP finished third, while Ducati Team's Andrea Dovizioso of Italy finished in the fourth place.
Quartararo has really impressed recently and was near to snatching a race win at Marquez's expense more than once, but the Spaniard managed to survive and claim the world title.
"Really frustrating, but really happy to be fighting with Marc," Quartararo said after the race.
"We know that this year apart from Austin (when Marquez crashed) he's always on the podium, and for many years he is the reference for MotoGP," he added.
The MotoGP season is ongoing with four more Grand Prix races remaining in Japan, Australia, Malaysia and Valencia.
Marquez sealed this year's world title with a tally of 325 points to top the overall standings, enjoying a 110-point advantage over Dovizioso.
( With inputs from IANS )