Portugal will fill a slot left vacant by Vietnam and be the third race of the Formula One season on May 2, the sport confirmed on Friday.
"We want to thank the promoter and the Portuguese Government for their hard work and dedication in getting us to this point," said Formula One chief executive Stefano Domenicali in a statement.
"We are confident and excited about our 2021 season, having shown last year that we could deliver 17 races safely and bring our millions of fans thrilling racing at a difficult time.
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We hope to welcome fans to Portimao again this season in a safe way and are working with the promoter on the details of that plan.
Last year's Portuguese race weekend was attended by 27,000 spectators.


The Azerbaijan Grand Prix in Baku will go ahead without spectators in June after being cancelled last year due to the Covid-19 pandemic.
A statement said it was still too soon for fans to attend safely, and tickets from 2020 would be valid for 2022 provided no refund had been sought.
"Our main priority this year will continue to be the health and safety of everyone working and participating at the event," said promoter Arif Rahimov.
The race had a reported three-day attendance of 85,000 in 2019, with overseas visitors accounting for almost a quarter.
It is scheduled to be the sixth round of the 2021 season, the June 6 date sandwiched between Monaco and Canada.
Azerbaijan is the first grand prix so far this year to confirm it will be behind closed doors. Most were held without spectators last year.
Tickets for the March 28 season-opener in Bahrain are being sold to fans who have been vaccinated or have recovered from the virus.
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