Heikal served as editor-in-chief of state-owned daily Al-Ahram from 1957 to 1974, and under his tenure it was considered the region's newspaper of record.
He had been ill for three weeks, and suffered fluid in his lungs and kidney failure, Al-Ahram reported on its website.
Heikal, who was born in the Nile Delta province of Qalubiya on September 23, 1923, authored more than 10 books on the conflicts and political intrigues of the region.
He initially backed Nasser's successor Anwar Al-Sadat, but was jailed in September 1981 after falling out with the president, who signed the first Arab peace treaty with Israel.
He took to the sidelines during Hosni Mubarak's three-decade rule, but would sometimes give interviews.
Speaking to British newspaper The Independent in 2007, he criticised the autocrat, who was toppled in a popular uprising four years later.
In December 2015, Heikal called on President Abdel Fattah al-Sisi to hold a political dialogue to tackle the country's crises, ranging from an economic downturn to militant attacks and political unrest.
Sisi, the former military chief, had overthrown the unpopular Islamist president Mohamed Morsi in 2013, unleashing a bloody crackdown on Islamists while contending with a jihadist insurgency.
The crackdown has extended to secular opponents.
"There are many people who accept what is happening, because the alternatives are bad, and they have experienced the alternatives," Heikal said in an interview with an Egyptian television host.
A statement from Sisi's office eulogised Heikal as having "enriched Egyptian and Arab journalism with his writings.
