In a communique, the Palestinian embassy in the Iranian capital said the former envoy passed away at a hospital "due to illness".
Zawawi served as the Palestinian ambassador to Tehran for 42 years (1980-2022) and retired in February last year due to failing health.
He was the second Palestinian envoy to Iran after the revolution, succeeding Hani al-Hassan.
One of the founder members of the Palestinian Fatah resistance movement, Zawawi was the longest-serving foreign diplomat in the Islamic Republic of Iran after the 1979 revolution, which earned him the title of 'Moghaddam al-Safra', meaning the 'senior-most foreign diplomat'.
Al-Zawawi passed away due to sickness, the Palestinian embassy said.
The embassy is scheduled to make announcement regarding the funeral service.
Early in January 2022, al-Zawawi retired as ambassador to Iran, abdicating four decades of his diplomatic mission.
Al-Zawawi was the second Palestinian ambassador to Tehran following the Islamic Revolution of 1979. He was one of the founding members of the Fatah political party.
Iranian Foreign Minister Hossein Amir Abdollahian delivered a message of condolence over his death.
Zawawi’s daughter, Salah al-Zawawi, who took over as Palestinian ambassador to Iran in 2022, received particular condolences from Iran’s top diplomat.
The foreign minister expressed sympathy over his passing and asked God to grant him eternal peace.