The event, held at the Movistar Arena, was to promote his 14th book, "The Construction of the Miracle", ahead of national midterms on 26 October.
Milei's appearance comes amidst public discontent, economic hardship, and a scandal involving an ally, José Luis Espert, who withdrew from the election.
Argentina is facing high inflation and difficulties meeting debt payments, with Donald Trump recently providing an emergency bailout of up to $20 billion.