TEHRAN, Young Journalists Club(YJC)_Iraq's al-Ahd news network reported on Friday that Iraqis from "all of the country's provinces" have gathered in the city.
The protesters were seen carrying banners and chanting slogans calling for the expulsion of US forces.
The demonstrators are planned to gather in the intersection of Baghdad University in the Jadriyah neighborhood.
According to Reuters, new checkpoints were installed across the capital by late Thursday afternoon in anticipation of the major rally.
Iraqis in Karbala city, south of Baghdad, were also seen boarding buses heading towards the capital.
The rally comes after Influential Iraqi Shia cleric Muqtada al-Sadr called on Iraqis to stage "a million-strong, peaceful, unified demonstration to condemn the American presence and its violations" last week.
On January 5, the Iraqi parliament voted overwhelmingly in favor of a resolution calling for the expulsion of all US-led forces in the country two days after Washington assassinated Soleimani and Muhandis.
Speaking on Thursday ahead of the planned rallies, Sadr called on Iraqis to mobilize and defend the country's independence and sovereignty.
"Oh women, men and youth of the country, the time is now upon us to defend the country, its sovereignty and dependence," Sadr said in a tweet.
"Spread the word of an independent future Iraq that will be ruled by the righteous; an Iraq which will not know of corruption nor aggression" he added, calling on Iraqis to expel the "tyrants".
Various Iraqi resistance groups affiliated with the country's Popular Mobilization Units (PMU) have also backed the anti-American rally.