Soleimani’s body was flown to the city of Ahvaz in southwest Iran.
IRIB posted a video clip of a casket wrapped in an Iranian flag being unloaded from a plane as a military band played.
Thousands of mourners dressed in black marched through Ahvaz, in live footage aired on state TV.
Soleimani, the architect of Tehran’s overseas clandestine and military operations as head of the Revolutionary Guards Quds Force, was killed on Friday in a US drone strike on his convoy at Baghdad airport.
While many Iranians have rallied in recent days to show grief over the death of Soleimani, regarded as the country’s second most powerful figure after Supreme Leader Ayatollah AliKhamenei, others worry his death might push the country to war with a superpower.
US President Donald Trump on Saturday threatened to hit 52 Iranian sites very hard if Iran attacks Americans or US assets.
The body of Iranian-backed Iraqi militia leader Abu Mahdial-Muhandis, who was killed in the attack with Soleimani, was also flown to Ahvaz, according to IRIB.