The presidents of Colombia, Bolivia, Ecuador and Peru, the vice-president of Suriname and the natural resource minister of Guyana attended the one-day summit in the jungle city of Leticia in southern Colombia.
Brazilian President Jair Bolsonaro participated by video link, while his foreign minister, Ernesto Araujo, attended in person.
"This meeting will live on as a coordination mechanism for the presidents that share this treasure - the Amazon," Colombian President Ivan Duque said at the signing, adding the countries will meet again at the United Nations Climate Change conference in December.
"Goodwill alone is not enough anymore," Peruvian President Martin Vizcarra added.
The countries will create a natural disaster network so they can better cooperate in the face of events like large-scale fires, the pact said.
The group will also work on reforestation initiatives, increase efforts to monitor deforestation activity via satellite, develop education initiatives and increase the role of indigenous communities in sustainable development, it added.
The countries also agreed to share information on activities like illegal mining that hurt conservation, the pact said.
The group will "work together to strengthen the programs and financial mechanisms, reiterate the commitments made by countries in these scenarios, mobilize public and private resources, including the multilateral banks, as appropriate, for the implementation of this pact."
Bolsonaro said in his remarks during the meeting that the pact was an affirmation of each country's sovereignty.
Meanwhile, Ecuadorean President Lenin Moreno opened by singing "Padre," a song by Spanish singer Joan Manuel Serrat about environmental destruction.
Forest fires in the Brazilian Amazon have surged in number by 83% this year, according to government data, destroying vast swathes of a vital bulwark against global climate change.
Some 60% of the forest is located in Brazil. The Amazon is also home to around 1 million people who are members of 500 indigenous groups.
