The endangered class of vertebrates includes frogs, toads, salamanders and caecilians — legless animals that resemble earthworms.
The plan represents the only hope of addressing an extinction crisis "unlike anything that the world has previously experienced," said the statement, issued by scientists meeting under the auspices of the International Union for Conservation of Nature and Natural Resources.
Nearly a third of amphibians, representing 1,856 species, are threatened with extinction and 122 others have been declared extinct since 1980, the scientists said.
The declaration appeals to "governments, the business sector, civil society and the scientific community for urgent and immediate adoption" of the plan.
The scientists called specifically for expanded research into a fungal disease, chytridiomycosis, which has decimated amphibian populations. They also urged efforts to document the range of amphibian species, combat global warming, protect key areas for amphibian survival and breed endangered species in captivity.
The conference described amphibians as playing an essential role in the planet's ecosystems by regulating insect populations that would otherwise damage crops or spread diseases. These animals are the proverbial "canaries in the global coal mine," the declaration stated.
"It is the worst crisis of the modern era," said Claude Gascon, vice president of Conservation International, which co-hosted the meeting.