The pilgrims with different nationalities performed mourning rites on Arbaeen, which comes 40 days after Ashura, the martyrdom anniversary of Imam Hussein (AS).
Most of the pilgrims had marched all the way to Karbala from cities like Najaf and Baghdad in a show of devotion.
According to the Iraqi sources, 15.5 million pilgrims were Iraqis, while 5.5 million others had travelled to Karbala from outside the country.
Iranians accounted for 60 percent of the foreign pilgrims, followed by travelers from Bahrain, Lebanon, Saudi Arabia, Kuwait, Pakistan and Qatar.
Around 300,000 security forces were tasked with ensuring the safety of pilgrims and countering the potential terrorist attacks.
Transportation services to the holy city of Karbala was provided by 60,000 vehicles, 24 trains and 140 airplanes.
600 reporters from different countries covered the news of the magnificent gathering.
No safety problem has been reported during the ceremony thanks to the large number of the security forces.