The cavity is the first major structure found inside the Great Pyramid since the 19th century, the research team said.
The chamber connects the burial site of the queen to that of the king and therefore it is possible that the chamber was used as a passageway between the two rooms.
The project has been exploring Khufu's pyramid since October 2015 with non-invasive technology using subatomic particle scans.
According to NPR, scientists just discovered a huge hidden hole in the Great Pyramid of Giza, and no one knows why it's there.
Egypt's former antiquities minister and famed archaeologist Zahi Hawass, who has been testing scanning methods and heads the government's oversight panel for the new techniques, said that the area in question has been known of for years and thus does not constitute a discovery.
"There have been many hypotheses about the pyramid, but no one even imagined that such a big void is located above the Grand Gallery", he said.
The secret chamber, which could date back to 2560 BC, is estimated to be some 30 metres (98 feet) long and could help explain how the tomb of the Egyptian pharaoh Khufu - after whom the pyramid was named - was built, the BBC reported.
Muons are made when cosmic rays from deep space hit the atoms of the upper atmosphere.
The goal of the space is unclear, and it is not yet known whether it was built with a function in mind or if it is merely a gap in the pyramid's architecture. These particles rain down and lose energy as they pass through materials - like the thick stones of the pyramid - and that makes them slow down and decay.
"In order to construct the Grand Gallery, you had to have a hollow, or a big void in order to access it - you can not build it without such a space", he said.
Muon detection has improved significantly since it was developed in the 1960s, so Tayoubi and his colleagues were able to use three advanced muon-detection techniques-nuclear-emulsion films, hodoscopes, and ardon gas-based detection. However, some historians are more excited than others about the discovery.
Tayoubi argues that the void is not a construction irregularity because blocks of varying sizes and shapes would have absorbed more muons that were detected.
Archaeology workers toil in front of the Great Pyramid, in Giza, Egypt, in 2010. However scientists could put additional muon detectors in the king's chamber to try and assess the void from alternate angles.