Mercedes won the constructors' world champion for the second year in a row but has already said it will leave the discipline next season.
Swiss Edoardo Mortara in a Venturi won the race and finished third in the championship behind Belgian Vandoorne and New Zealander Mitch Evans in a Jaguar. "It's the best feeling ever," said Vandoorne a 30-year-old former Formula 1 driver. "It's been a great season and the team has done a great job.
Mitch and Edoardo have been pushing me all season but it's all been about consistency. They have more wins than me but I have more podiums." Although he has only won once this season, in Monaco, Vandoorne scored points in 15 of the 16 races and finished on the podium seven times.
He succeeds his Mercedes teammate, Dutchman Nyck de Vries as x=champion. The "Gen2" single-seaters will make way next year, the ninth season of the championship to "Gen3" cars that will be lighter, more powerful and run longer.