The win by Martinelli, of the opposition Alliance for Change, marks a rare center-right election triumph in a region that has seen a wave of leftist leaders.
Electoral Tribunal President Erasmo Pinilla called Martinelli the "indisputable winner" after preliminary results Sunday showed him with 61 percent support and ruling-party candidate Balbina Herrera with 37 percent.
Conservative candidate Ricardo Martinelli has won Panama's presidential elections, promising to guide the country through the world economic crisis and an ambitious expansion of the Panama Canal.
In a parallel parliamentary vote on Sunday, Herrera's PRD appears to have won a majority in the 71-seat Congress, creating an opposition that could complicate Martinelli's rule.
Martinelli, who owns Panama's largest supermarket chain, said he would work for a national unity government.
"We can't continue to have a country where 40 percent of Panamanians are poor," he said in a victory speech.
His win means that Martinelli will get to oversee a massive 5.25-billion-dollar (3.94 billion euros) project to expand the congested Panama Canal.
The 80-kilometer inter-oceanic waterway handles an estimated five percent of world trade, and most of the trade in goods between China and the east coast of the United States.
