Globo's G1 news portal cited a study by the TripAdvisor travel website that rates in the swish Copacabana beachside district had been hiked by up to 229 percent.
The study says average hotel accommodation prices in the district will hit a wallet-busting 1543.99 reais ($650) per night on match days during the June 12 to July 13 competition.
For Rio as a whole the nightly average will be 1,077 reais for rises topping 100 percent, making rooms even more expensive than Times Square in New York, according to estimates.
Rio will host seven matches -- including the final.
"This is not good for the city, as it underpins the idea that tourists are being exploited," G1 quoted Alfredo Lopes, chairman of the Rio Hoteliers Association, as saying.
"We recommend that hotels indicate on their sites the rack rate they used on December 31 and during Carnival (official peak periods) and also for the World Cup, added Lopes.
In January, government-backed consumer groups reached a deal with Brazilian hoteliers that prices should not exceed New Year and carnival tariffs, though that would only mean prices not rising above around $1000 a night.
The TripAdvisor study also showed up huge price variations at Salvador de Bahia in Brazil's northeast of up to 212 percent above normal rates on match days while mark-ups for Belo Horizonte and Fortaleza also topped 100 percent.
Brazil expects some three million domestic tourists to criss-cross the giant nation during the World Cup along with some 600,000 foreign tourists.
Despite a rise of some 168 percent tourism-derived receipts over the past decade Brazil only receives some six million foreign visitors annually.
That compares with 80 million for top-ranked destination France.