President of chad Mahamat Idriss Deby gestures as he arrives for a meeting over security in the Sahel region at the Elysee Palace in Paris, France, on Nov. 12, 2021. AP
Prime Minister Benjamin Netanyahu's office called the embassy's inauguration in Ramat Gan near Tel Aviv "a historic moment".
Netanyahu said in 2020 that he had discussed "the possibility of opening an embassy in Jerusalem" with a Chadian delegation.
That would have been a coup for the right-winger who has been pressing foreign governments to set up their embassies in the city, since then president Donald Trump moved the US embassy in 2018.
"We are strengthening our friendship and our common interests in pursuing peace, security and prosperity," Netanyahu said Thursday.
Israel recognised Chad when it declared independence from France in 1960 and by 1962 had opened an embassy in Ndjamena.
Ties between Israel and Chad were broken in 1972 amid pressure from Muslim African nations.
The Arab-Israeli wars of 1967 and 1973 led a number of African states to sever relations with the Jewish state.
But in recent years, Israel has highlighted areas of cooperation ranging from security to technology and agriculture to improve ties on the continent.
In a 2019 visit to Chad, Netanyahu and Deby announced a resumption of diplomatic relations.
After his arrival on Tuesday, Deby met the head of Israel's Mossad spy agency, David Barnea.
The Mossad "has played a central role in formulating the agreement and strengthening relations between the two countries," a statement from the Israeli prime minister's office said.
One of the world's poorest countries, Chad is not an Arab League member state but belongs to the Organization of Islamic Cooperation (OIC).
Netanyahu has made broadening Israelis ties across the Arab and Muslim world a foreign policy priority.