Metro.co.uk reports the Boeing 777 managed to avoid the unmanned balloon and land safely on Sunday (July 3).
The plane was carrying up to 300 passengers at the time, many of whom, along with plane spotters, noticed the large ballon coming close to the jet's flight pattern.
"The ballon caught the attention of those on board," a passenger told local outlets via Metro.co.uk.
"The Boeing 777 came in a little misaligned with the runway to avoid the balloon," added Rafael Freitas, who took photos of the near-accident from São Paulo Guarulhos Airport. "When it had passed the balloon, it turned to correct its alignment."
The balloon is believed to have previously been used at a local festival prior to the incident on Sunday.
A spokesperson for Qatar Airways confirmed the airline was "aware of an event concerning one of its aircraft involving an unmanned balloon before landing in São Paulo" on Sunday.
"The flight landed as normal and safety margins were maintained at all times," the spokesperson added via Metro.co.uk. "The captain filed a report following the flight which is now being investigated by the Brazilian authorities."