The pharaoh is believed to have enjoyed the longest rule of his time more than 3,600 years ago.
The tomb, which dates back to 1650 BC, was found near the city of Sohag around 300 miles to the south of Cairo. The pharaoh's skeleton was found intact within a wooden sarcophagus but looters are believed to have taken most of the other items of value long ago.
Thought to have ruled at the beginning of the 13th Paranoiac dynasty, King Seneb Kay led his people for more than four-and-a-half years. Archaeologists were able to decipher hieroglyphics inscribed on the walls to learn who the tomb had belonged to.
"This adds to our pharaonic history, and sheds light on an era about which we knew very little previously," said Head of Antiquities Ali al-Asfar. "He was originally mummified but his body was pulled apart by ancient tomb robbers."
The tomb's discovery follows that of an ancient Egyptian brewer that was discovered on the west bank of the Nile earlier this month.