The four national presidents committed to creating a local organizing committee with a representative from each country to coordinate with CONMEBOL, South American football's governing body.
The first meeting will be in Buenos Aires on April 8.
They also decided to distribute the opening match, two semi-finals and final between the four potential hosts.
Argentina and Uruguay originally announced their intention to submit a joint bid in 2017 before Paraguay joined the coalition later that year.
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Chile was added to the joint candidacy last month while Bolivia, led by football-mad President Evo Morales, has also shown an interest in forming part of the bloc.
Argentina's Mauricio Macri, Sebastian Pinera of Chile, Paraguay's leader Mario Abo and Uruguay president Tabare Vazquez met with CONMEBOL chief Alejandro Dominguez on the margins of the UN summit on South-South cooperation in the Argentine capital.
"We want to consolidate this idea and start to work on delivering the objective that the World Cup in 2030 is played here in the country and in the continent where it was born," Dominguez told AFP.
The first ever World Cup in 1930 was played in Uruguay, with the hosts beating neighbors Argentina 4-2 in the final.
The South American bid faces competition from Morocco and potentially several other joint bids, including one from Britain and Ireland and another by an eastern European confederation of Greece, Serbia, Bulgaria and Romania.
"We know that we're up against tough competition, which is why we have to start working as soon as possible," said Macri.
Alongside Uruguay, both Chile, in 1962, and Argentina, who claimed a first world title on home soil in 1978, have also previously hosted the sport's global showpiece.
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The host is due to be decided during the 2022 World Cup in Qatar. The winning 2026 bid was also a team effort. The tournament will be held in the US, Canada and Mexico.
The 2030 edition should feature 48 teams from the six continental unions, whereas the inaugural World Cup was contested by just 13 teams from three regions.
Even so, Vazquez said this challenge will be "much less difficult than what it meant to assume 100 years ago" the responsibility of organizing the very first such event.
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