Fans have spent 1.03 billion reais ($320 million) on tickets, representing 96 per cent of the target set by the Rio 2016 organising committee, Xinhua news agency reported.
Some 6.1 million tickets were made available for the Games. According to organisers, ticket sales revenue is expected to make up 16 per cent of the cost of running the Olympics, which run from August 5 to 21.
The figures were presented in a report to the International Olympic Committee during its last meeting with organisers before Friday's opening ceremony.
The report also included an update on unfinished construction work at the Olympic village, which prompted some delegations to delay their arrival.
"Everything is on track," Rio 2016 president Carlos Nuzman said.
"All Games have problems. The forecast is that within three, four or five days, we will correct a lot of things," he added.