Clinton met with Haitian President Rene Preval outside a tent at the Port-au-Prince airport after indicating she wanted to leave vehicles free to carry out relief work, CNN reported.
"We are here at the invitation of your government to help you," she said. "As President Obama has said, we will be here today, tomorrow and for the time ahead."
Haiti's ambassador to the United States, Raymond Joseph, said Clinton's visit to Haiti is essential for coordinating aid efforts in the wake of Tuesday's devastating 7-magnitude earthquake.
"I think her presence there will help smooth operations between the Haitian officials -- some who are reticent in relinquishing some power -- and U.S. officials," Joseph said.
Countries offering aid include Belize, Brazil, Britain, China, Chile, Spain, Canada, Israel, Iceland, Ireland and Morocco, CNN said.
The Israel Defense Forces opened a field hospital in an abandoned football field with the expectation of treating 500 wounded a day.
Friday the USS Carl Vinson arrived off the coast. It is carrying 51 hospital beds, three operating rooms, 19 helicopters and the ability to produce hundreds of thousands of gallons of drinking water per day.