Speaking at the launch ceremony, close to the giant telescopes of the Paranal Observatory on the top of Cerro Paranal, the leaders vowed to forge close economic ties and push for more trade with the emerging markets of the Asia-Pacific region.
Several regional organizations have declared similar aims in the past but advocates for the Pacific Alliance say the timing is right for closer Latin American-East Asian links because of rising growth rates on both sides of the ocean.
The Cerro Paranal setting in the Atacama Desert provided the politicians with opportunities to underline the lofty ideals of their new venture.
The new agreements bind the four nations in a program of eventual economic integration.
Supporters for the accord hailed the signatory nations as the most open and outwardly focused economies of the region and cited contrasts with the Mercosur trade bloc, riven by petty rivalries, tit-for-tat trade curbs and unequal economic performance of member states.
Chile, Colombia and Peru have associate status in Mercosur, which is looking eastward to forge closer trade links with Europe.
In addition members of the new alliance also have connections with older groups, including the Andean Community and the Union of South American Nations.
"From the heights of Paranal, in the most arid desert in the world and under the clearest of skies, we have signed a pact officially giving birth to the Pacific Alliance," Chilean President Sebastian Pinera declared at the opening ceremony.
Pinera was host to Mexican President Felipe Calderon, Peru's Ollanta Humala and Colombia's Juan Manuel Santos, as well as the presidents of Costa Rica and Panama, Spain's King Juan Carlos and Canadian Foreign Minister John Baird.
Costa Rican President Laura Chinchilla said the country would seek to become a member of the new alliance.
Officials said the Pacific Alliance saw its potential as a major regional player with more than 215 million consumers and a combined gross domestic product of more than $2 trillion. The idea of the new pact was floated last year at a previous summit in Lima, Peru.
The leaders spoke of deep integration and fast-track engagement with the Asia Pacific region both to boost export earnings and to build multifaceted ties with the region stretching from China, South Korea and Japan to the Philippines and Australia and New Zealand.
Early news of the new pact received warm welcome in East Asia but Latin American economic strategists say they are more interested in boosting their own exports rather than becoming net importers from Asia.
Calderon and Santos said the Pacific Alliance would set in motion major moves toward regional integration. It wasn't aimed at any other regional group, Santos said, and would welcome wider links with other pacts -- a reference to Mercosur, the Andean Community and the Union of South American Nations.
"There are no incompatibilities or exclusion vis-a-vis other integration efforts," Santos said. "We are against nobody but rather in favor of even greater integration."
Analysts said the alliance could be a rebuff to Argentina and Brazil, accused of restrictive trade practices that have left smaller neighbors unhappy and looking for alternative markets.