The leaders from Nauru, Kiribati, the Federated States of Micronesia, Solomon Islands, Tonga, Tokelau and Tuvalu attended, along with the foreign minister of the Marshall Islands.
Fiji's Prime Minister, Frank Bainimarama -- who founded the PIDF three years ago -- says they have found a collective voice to demand, in the strongest terms, that the world finally face up to climate change.
In the declaration, the leaders say they are gravely distressed at the threat climate change poses to their countries' existence, and express their concern that not enough is being done, despite overwhelming scientific evidence.
Mr Bainimarama says the declaration will be presented to world leaders at the UN Climate Change Summit in Paris in 13 weeks time.
Meanwhile, François Martel has been appointed as the PIDF's Secretary General.
Next week all of the leaders, bar Mr Bainimarama, will attend the larger Pacific Islands Forum summit in Port Moresby, where climate change is also on the agenda.