The crowd in Baghdad was also there to mourn the death of Abu Mahdi al-Muhandis, the second-in-command of Iraq's Popular Mobilization Front (PMF), who was also killed in the Friday airstrike near the Baghdad International Airport, the BBC reported.
The gathering in Baghdad on Saturday marked the beginning of days of mourning for Soleimani, who was the head of the Quds Force of Iran's Islamic Revolution Guards Corps (IRGC).
Mourners started gathering in Baghdad from early Saturday morning, ahead of the start of the procession, waving Iraqi and militia flags and chanting "death to America".
The procession then snaked though the streets, some carrying portraits of Soleimani and some of Iran's supreme leader, Ayatollah Ali Khamenei.
Meanwhile, Iran's Deputy Ambassador to Baghdad Mousa Tabatabaie told Tehran's state-run IRNA news agency that funeral processions for Soleimani would also be held in the Iraqi holy cities of Najaf and Karbala on Saturday, reports Press TV.
Soleimani's body will arrive in Iran on Saturday evening where authorities have declared three days of mourning.
According to Iran's Mehr News Agency, a funeral procession for the IRGC commander will also take place in Tehran on Sunday morning, during which Khamenei will participate in a prayer ceremony.
The body will then be taken for burial in the city of Kerman, Soleimani's birthplace.
Khamenei and Iranian President Hassan Rouhani have vowed to retaliate against the US over Soleimani's death.
Friday's attack came after Iraqi protesters on Tuesday stormed the US embassy compound in Baghdad to protest the American air raids conducted on December 29 against five bases of Iran-backed militias in Iraq and Syria, claiming the lives of 25 people.
( With inputs from IANS )