UNESCO chief Audrey Azoulay says she has received Israel's official letter announcing its exit from the U.N. cultural body.
Israel previously said it intended to leave the Paris-based agency, citing "systematic attacks on the Jewish state."
Azoulay said in a statement on Friday she deeply regretted the withdrawal, which is set to take effect on December 31, 2018.
She added: "It is inside UNESCO and not outside it" that countries can overcome their differences.
According to AP, Israel's decision came on the heels of the United States announcing its withdraw from UNESCO over similar allegations of anti-Israel bias at the agency, where the Jewish state and its allies are far outnumbered by Arab countries and their supporters.