"I came here to confirm our affection and our commitment to Haiti.
"The fact that we could walk and run with these people is a great feeling," he said, referring to the warm welcome he received.
Many in the welcoming crowd were supporters of ousted former president Jean-Bertrand Aristide and ran alongside Chavez's motorcade through the streets of the capital.
Some reached out and touched the Venezuelan leader, breaking through a police escort to make contact as he saluted onlookers.
"When Chavez says he wants to help Haiti, he really means it and he proves it," said Magalie Demosthenes, waving a Venezuelan flag.
"We've invited and keep inviting the nations of the Caribbean, in this case Jamaica"
Hugo Chavez, Venezuela's president, during his visit to Jamaica
"He does not do like some rich countries which have to humiliate you before giving you anything."
Bush is unpopular among Haiti's poor, many of whom believe the US helped overthrow Aristide, who fled Haiti in February 2004 in the face of an armed revolt and under US and French pressure to quit. He now lives in exile in South Africa.
Haiti has joined a Venezuelan programme called Petrocaribe, which provides preferential financing terms for oil.
Preval said the deal would save Haiti $150m a year, money that could be spent on desperately needed social programmes.
Venezuela has agreed to give Haiti about $120m in grants for construction projects and social programmes, and in a joint donation with Cuba will give Haiti five electricity-generating plants.
Chavez had earlier stopped in Jamaica, where he called for the Caribbean to support his Alternative for the Americas, a pact designed to counter free trade deals proposed by the US.
"We've invited and keep inviting the nations of the Caribbean, in this case Jamaica," he said.
"Only truly united can we be free, sovereign, really independent."
Portia Simpson Miller, Jamaica's prime minister, signed a deal with Chavez under which Venezuela will supply Jamaica with liquefied natural gas starting in 2009, said Philip Paulwell, the energy minister for Jamaica.
The agreement comes three weeks after Patrick Manning, Trinidad's prime minister, said his country could not supply Jamaica with 1.1 million metric tons of the gas it needs.
"We approached Venezuela in the context of the Petrocaribe agreement, and they have responded favourably," Paulwell said shortly after Chavez left.