The rally was held to celebrate the success of Salvini's Northern League party in this year's general election, which saw the populist and euroskeptic party enter into a coalition with the anti-establishment Five Star Movement.
Salvini told about 50,000 supporters in Piazza del Popolo that the current government would last for five years. But the event had the markings of a campaign rally throughout, with the Interior Minister telling the crowd that "United we will win" as he finished his speech.
A vocal opponent of same-sex marriages, which are not legal in Italy, Salvini also promised a return to Italy's traditional roots, saying: "We will be be judged by the number of cribs we fill, with babies born not to Parent one or Parent two but to a mother and a father."
Italy is facing disciplinary proceedings from the European Commission over its proposed budget, which the bloc says does not comply with fiscal rules on EU member states.
"We are afraid of nothing and nobody," Salvini said of the dispute, while supporters waved flags adorned with the "Italians first" slogan, according to Agence France-Presse.
He also chided European regulations on so-called Made in Italy products and foods, saying: "We need a new EU based on respect, work and progress."
The event came days after Italy passed the so-called "Salvini decree," which removed migrants from the country's "welcome centers" and essentially made them homeless.
Barbie Latza Nadeau and Livia Borghese reported from Rome. Rob Picheta wrote in London.