There was doubt over whether the north-eastern cities would have their new stadiums ready for the tournament, which takes place in June 2013 and is considered a dry run for the World Cup the following year.
But FIFA said the two cities, along with the capital Brasilia, Belo Horizonte, Fortaleza and Rio de Janeiro, should be ready to host matches and gave them until mid-November to prove they are on track.
"We are quite confident that this Confederations Cup will be played in the six cities," FIFA Secretary General Jerome Valcke said at an announcement ceremony in Rio, which will host the final match of both the Confederations Cup and the World Cup.
The ceremony marked Valcke's first public appearance in Brazil since he angered Brazilian officials in March by criticising the pace of preparations for the World Cup. His remarks chilled relations between FIFA and Brazil, and led the Brazilian government to briefly declare him persona non grata.
The Confederations Cup features FIFA's six regional champions along with the host nation and the World Cup holders.
Spain, Japan, Mexico and Uruguay have all qualified for next year's tournament. The winners of next month's European Championship will join them, as will hosts Brazil and the winners of the Asian and African cups.
Brazil will kick off the tournament in Brasilia's 70,000-seat Mané Garrincha Stadium on June 15 and the final will be played at Rio's famous Maracanã stadium on June 30.
Although officials say Salvador (pictured) is 60 percent complete and Recife is 40 percent done, the Folha de S.Paulo newspaper earlier this month quoted internal FIFA documents saying there was a "high risk" that Recife will not be ready in time.
Wednesday's announcement was meant to allay those fears.
"We are committed to delivering the greatest FIFA Confederations Cup ever," said former Brazil striker Ronaldo, who is one of the local organisers.
"It is a big challenge for the six host cities, who have worked so hard to come to this point. But their effort will surely pay off with memorable matches, great celebrations and the huge international awareness that the tournament will raise for these cities."
