The Dutchman, who wrapped up the title last month in Japan with four races to spare, was unchallenged as he led from pole position to chequered flag.
The race, scheduled for November 21 at the floodlit Losail International Circuit, will form part of an unprecedented Middle Eastern quartet of Grands Prix on the 22-race 2021 calendar.
Bahrain, which is hosting the second round of the Formula One season on March 22, has reported 83 cases of the virus, mostly linked to people who had travelled to Iran.
Lewis Hamilton is now only seven wins short of Michael Schumacher's all-time record of 91.
It was the 11th victory of the year for Hamilton, who dominated the race with a controlled drive.