The decision effectively ends two months of legal battles over accusations of fraud.
The federal electoral tribunal approved a ruling that said Calderon had a winning margin of 235,000 in the closest election in Mexican history.
That is around 10,000 votes less than the original margin of victory and follows recounts at around nine percent of polling stations and the annulment of some ballot boxes.
Although the tribunal's decision cannot be appealed, protests by supporters of Andres Manuel Lopez Obrador, the popular former Mexico City mayor who has alleged there was widespread fraud in the counting of ballots, are expected to continue.Lopez Obrador has called for the election to be annulled, and insists he will not recognise Calderon as president, even indicating he might form a parallel government.
"Imagine where we'd be if we only went by what the [electoral] tribunal decided," Lopez Obrador told supporters on Monday.
Tension has been high since
the election on July 2
"Civil resistance," he said, "goes beyond" fighting against electoral fraud.
Lopez Obrador's backers set up a tent city in Mexico City's central Zocalo Square, and he has camped out since July 31 in a yellow tent facing the presidential palace.
The encampment has blocked a major thoroughfare for weeks, disrupting traffic and business in the Mexican capital at an estimated cost of $364 million dollars and 5,000 jobs, according to business leaders linked with Calderon's National Action Party (PAN).
Lopez Obrador says he plans to lead a mass protest downtown on Mexico's independence day, September 16.
Authorities have urged his supporters - particularly the 126 members of his party in Mexico's parliament - to accept defeat, which will allow a peaceful handover of the presidency on December 1.
However, the current president, Vicente Fox, also of PAN, on Monday rejected the use of the army to remove protesters.
"Democracy has not allowed and will never, never allow, the use of the army against the public"
Vicente Fox, outgoing president
"Democracy has not allowed and will never, never allow, the use of the army against the public," he told a group of cadets.
For his part, Calderon insists he won the vote fairly, albeit by the narrowest of margins. International observers have also deemed the election free and fair.
Calderon defeated Lopez Obrador by 239,751 votes, a margin of just 0.57 percent, with around 41.7 million votes cast.
After studying Lopez Obrador's 375 objections to the vote, the panel agreed to recount only nine percent of ballots instead of all of them, as demanded.
Lopez Obrador has since declared the tribunal unqualified to pass judgment and kept up his protest campaign.
Calderon has always insisted
he won the vote fairly
But poll results Monday showed that most Mexicans frown on his tactics.
The survey published by the El Universal newspaper found that 71 percent of respondents disapprove of his protests and civil disobedience, while just 23 percent supported them. The poll surveyed some 1,000 registered voters.