The fund will promote alternatives to forest-clearing for people living in the Amazon and support conservation and sustainable development. But a government minister said Brazil would not accept foreign interference in its Amazon policy.
The environmental group Greenpeace said it was the first time Brazil had accepted a link between global warming and preserving the rainforest.
Speaking at the launch in Rio de Janeiro, Lula said Brazil was aware of how much the Amazon meant to the wider world.
"It's better for the country's image to do things right, so we can walk in international forums with our heads high," he added.
But the Brazilian leader also insisted that the Amazon's preservation was Brazil's responsibility.
"We… want the sovereignty that we hold over Amazonian territory and the decisions that are made in this region to be respected," he said.
Roberto Mangabeira Unger, minister for strategic affairs, put the point more forcefully:
"The fund is a vehicle by which foreign governments can help support our initiatives without exerting any influence over our national policy. We are not going to trade sovereignty for money."
Greenpeace in Brazil said that the country was accepting the link between global warming and preserving the forest for the first time.
"For a long time, Brazil was violently opposed to this, insisting fossil fuel was to blame," said Sergio Leitão, director of public policies for Greenpeace Brasil. "That's true, historically speaking, but today forests play an important role," Leitão said.
Brazilian Environment Minister Carlos Minc called for a radical change in environmental attitudes: "We are committed to reducing the destruction of the rainforest, to eliminating illegal burning and to guaranteeing a better quality of life for all.
"Our war is not won by simply reducing illegal burning in one month, it will be won once this environmental model that is destroying our communities and biodiversity is history."
The Amazon rainforest is the largest continuous tropical forest, shared by nine countries, 65% of which is Brazilian territory.
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