Organisers said around 80,000 people attended — many travelling from around the country — waving flags and banners with slogans such as “Italians first”, “Italy raises its head” and “Six months of common sense government”.
The 45-year-old Salvini, who is also deputy prime minister, referenced the “yellow vest” protests rocking neighbouring France.
“Those who sow poverty reap protests, those who sow false promises reap the response of those on the margins and the countryside,” he told the cheering crowd.
Salvini also lashed out at the European Union, which is in a stand-off with his government over Rome's anti-austerity budget that has been rejected by Brussels because it sharply increases spending and the deficit.
“We are afraid of nothing and nobody,” Salvini said of the dispute.
Taxi driver Stefano Feliziani, 63, who was wearing a yellow vest in the crowd, said he was a “Salvinian” who stands with those fighting against the “usurocracy, the government of banks, the single mindset of globalisation”.
Salvini's League has surged in popularity since taking power in a coalition government earlier this year, with opinion polls putting the party on 30 percent, up from the 17 percent it won in March elections.
Gabriele Accornero, a 49-year-old online marketing specialist from the northwestern town of Avigliana, said the anti-migrant Salvini had “managed to stop illegal immigration, he is the first who kept this promise”.
“It's not racism, it's just that we could not end of up with all of those delinquents,” she said.