The death of one of the founders of the Amal Movement, a prominent Shiite political party and former militia, was mourned by people across Lebanon’s political spectrum.
As speaker of parliament in 1989, he is regarded as the godfather of the Taif Agreement, which paved the way towards the end of the 1975-1990 war that killed 120,000 people and led many more to leave Lebanon.
He served as secretary general of Amal from 1978 to 1980, taking over from fellow founder Musa Al Sadr, who disappeared in mysterious circumstances in Libya in 1978.
When he resigned as secretary general, he was replaced by Nabih Berri, who remains as leader of the party to this day.
Mr El Husseini was appointed as parliament speaker from 1984-1992, with Mr Berri again taking his place, reportedly because he was preferred by the Syrian forces who were occupying Lebanon at the time.
Regarded as a moderate politician, Mr El Husseini first became an MP representing Baalbek-Hermel in 1972 and remained in place until 2008, when he quit over a political deal agreed by Lebanese politicians in Doha to defuse a crisis that had led to renewed conflict.
Lebanon has declared three days of mourning and Mr Berri has cancelled Thursday’s parliamentary session, where MPs were to meet to elect the country’s next president.
Caretaker prime minister Najib Mikati said Mr El Husseini had played a “pioneering role” in bringing about the Taif Agreement, adding that Lebanon had lost an important “national and constitutional figure”.