The prisoners include Lebanese who had gone to fight with rebels and jihadists against the forces of longtime ruler Bashar al-Assad during the conflict, which began in 2011, and were arrested upon their return to Lebanon.
The rally in Tripoli's Nour Square comes nearly a month after Islamist-led forces toppled Assad.
"We want to increase pressure on the Lebanese authorities to release all Islamist detainees," said protester Ahmad al-Shimali.
"Islamist detainees in Lebanon's prisons were arrested in the context of the Syrian revolution," he said of the more than 13-year civil war.
"Most went to Syria to fight, supported our people in Syria, or were found to have communicated with jihadists or fighters," Shimali added.
"But today the Assad regime has fallen."
Rights campaigners have long demanded fair trials for those accused of ties to Islamist extremism in Lebanon, some of whom have been behind bars for years without a trial.
In late December, Prime Minister Najib Mikati told relatives of the detainees that the issue should be "definitively" resolved, but also said parliament must first decide on whether to issue a general amnesty.
Parts of Tripoli saw clashes in the early days of the war in Syria, which was triggered by the Assad government's repression of democracy protests.
Tensions had been simmering for years between the city's Sunni Muslim district of Bab al-Tebbaneh and nearby Jabal Mohsen, where the majority of residents are from the minority Alawite sect, an offshoot of Shiite Islam to which Assad belongs.
