Portugal's Portimao circuit, in the Algarve, will host a Grand Prix for the second time in its history.
Portugal will fill a slot left vacant by Vietnam and be the third race of the Formula One season on May 2, the sport's body has confirmed.
The race will again be held at the Algarve circuit near Portimao that made its debut last October on a calendar reduced to 17 races as a result of cancellations due to the Covid-19 pandemic.
That was the first Portuguese Grand Prix in 25 years.
"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 on Friday.
"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.
"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."
27,000 spectators attended last year
Twenty-seven thousand spectators were in attendance last autumn when Lewis Hamilton won his record-breaking 92nd Grand Prix and the organisers are keen to replicate that in spite of current coronavirus restrictions.
The season is set to start in Bahrain on March 28 and features a record 23 races. The Australian Grand Prix, which was scheduled to open the season on March 21, has been postponed to November 21.
Another postponed race, the Chinese GP, which was initially set for April 11, has not been rescheduled.