The exhibition, which will include gold jewellery from King Tutankhamen's tomb, will be part of the museum's centenary celebrations.
The museum was opened on its present site in the heart of the city in 1902 to store antiquities to stop them being plundered.
"We have been digging inside the basement of the Cairo museum and we have been digging inside the stores of about 15 major sites in Egypt. No one has seen these artefacts before," Zahi Hawass, director of the Supreme Antiquities Council said.
"We found about 40 artefacts of King Tut never shown before."
The museum already exhibits Tutankhamen's famous golden death mask as well as ancient items from the country's other pharaohs and eras in history.
President Hosni Mubarak is expected to attend the cultural and artistic celebration being planned for 9 December to mark the museum's 100th anniversary.
The institution will also be renovated as soon as the celebrations are over, and will last for seven months.
"We will not only celebrate this centennial anniversary but we will move the museum from 1902 to 2003," Mr Hawass said.
"At the moment, if you visit the Egyptian Museum in the summer it is like visiting hell.
"This is not good for the artefacts or the visitors so we are adding air conditioners."
The museum will lose many of its main treasures when a new Grand Egyptian Museum on the outskirts of the city opens in about five years.