FIFA said Belo Horizonte, Brasilia, Fortaleza, Recife, Rio de Janeiro and Salvador would host matches in the eight-team competition even though some of the stadiums would not be ready until four months before the tournament begins.
Football's governing body had stated that venues had to be completed six months before the event kicks off but it has relaxed the rules to allow the host country an additional eight weeks to get the stadiums ready.
FIFA Secretary-General Jerome Valcke last week said stadiums should be delivered within the allotted time frame so that organisers could hold at least two test events.
The tournament, featuring the champions of the country groupings that make up FIFA's six "confederations," will be closely watched as a major test ahead of Brazil's hosting of the 2014 World Cup.
FIFA and Brazil have been at loggerheads over preparations for the World Cup, to be held in 12 Brazilian cities, because of construction delays, organisational uncertainty, and disputes over an alcohol ban in stadiums and ticket discounts for students and senior citizens, both of which are mandated by Brazilian law for sporting events.
Many in Brazil are also worried that logistical hassles could complicate the World Cup, which is expected to attract as many as 600,000 foreign visitors in addition to the crush of locals who will be attending games. Despite government promises to modernise the country's aged and overburdened roads and airports, routine travel in Brazil remains plagued by delays.
Stadiums in Rio de Janeiro, Brasilia, Recife and Salvador are not expected to be ready until four months before the Confederation Cup kicks off on June 15.
Officials on Thursday said they remained concerned but had decided to move ahead after assurances by Brazilian authorities.
FIFA was "convinced by the words and guarantees delivered by the representatives of the six cities," said Jose Mara Marin, the head of the local organising committee, at a news conference in Sao Paulo.
Marin said that FIFA would closely monitor construction, with cameras tracking work in real time and officials visiting every stadium weekly.
The relaxed timetable comes as a particular relief to the northeastern city of Recife, which FIFA had threatened to scrap as a venue. The city's Arena Pernambuco has suffered delays and cost overruns and originally was not on track to be completed until December 2013.
Brazilian officials, however, decided to speed up construction of the 46,000-seat facility to ensure the city took part. The stadium was now 71 percent ready, builders Odebrecht said this week without disclosing how much accelerated delivery would increase an original cost forecast of 500 to 532 million reais ($246.3 to $262.1 million).
Italy, Japan, Mexico, Tahiti and Uruguay have all qualified to take part in the Confederations Cup and will be joined by host country Brazil, world champions Spain and the winners of next year's African Nations Cup.
