The protocol was signed during a meeting between Greek Prime Minister Kyriakos Mitsotakis and the presidents of Egypt, Abdel Fattah al-Sisi, and Cyprus, Nicos Anastasiades, in Athens.
The deal concerns the "interconnection" of the neighbors and transfer of electricity to their respective networks, Mitsotakis said, adding that "as energy sources diversify, Egypt can become a supplier of electric power, which will be mainly produced by the sun, and Greece will become a distribution station for Europe."
The announcement comes as countries around the world face an energy crisis, with the prices of natural gas, oil and coal rising.
Sisi said the agreement aims to "reinforce energy cooperation."
In a joint statement, the Mediterranean neighbors said: "This interconnection reinforces cooperation and energy security, not only between these three countries but also with Europe."
The three countries also expressed their intention of exploring and transferring natural gas in the region.
Energy cooperation between eastern Mediterranean countries regularly irritate Turkey, which has its eyes set on oil and natural gas deposits in the region.
"Unfortunately, Ankara does not understand the message of the times and its aspirations to the detriment of its neighbors are obviously a threat to peace in the region," Mitsotakis said.
Tensions soared in 2020 when Turkey sent an exploration ship and small navy flotilla to conduct research in waters that Greece considers its own under treaties.
The Turkish foreign ministry later on Tuesday lambasted the joint statement as another example of the "hostile policy" toward Turkey and Turkish-held northern Cyprus.
While Ankara supported energy projects which "increased cooperation between regional countries," the ministry stressed that Turkish and northern Cyprus' rights and interests "should not be ignored by these projects."