"This is a protest against those who support the publication of caricatures of the Prophet Muhammad," the region's leader Ramzan Kadyrov told the rally in the capital Grozny on Monday.
"This is a protest against those who insult the Muslim religion."
Demonstrators chanted "Allahu Akbar" (God is Greatest) and released balloons into the sky at the highly choreographed event, as speakers harangued Western governments for allowing publications to print caricatures of the prophet, Al Jazeera reported.
Kadyrov - a loyalist of President Vladimir Putin - on Sunday said that he expected hundreds of thousands of people to attend the meeting and live footage on Russian state television showed demonstrators filling Grozny's main square.
The protest was the latest to take place in the Muslim world over the latest publication of a Prophet Muhammad cartoon by the French satirical weekly Charlie Hebdo.
The magazine ran the cartoon a week after an attack on its offices, the first of a spate of attacks that eventually left 17 people dead in and around Paris in three days.
The Paris attacks shocked the country and sparked an outpouring of international support, with many newspapers and magazines around the world reprinting Charlie Hebdo cartoons.
Many Muslims see any depiction of Islam's prophet as offensive and the publications have sparked sometimes violent rallies in countries from Pakistan to Niger.
Russia's media watchdog on Friday warned publications that printing cartoons of the Prophet Muhammad was against the country's law and ethical norms.