The decision was taken during Friday's virtual leaders' summit to mark the fifth anniversary of the Paris Agreement.
The leaders have endorsed the development of a 2050 Strategy for the Blue Pacific Continent ahead of next year's COP26 in the UK.
The leaders also renewed their commitment to progress the implementation of the Paris Accord.
The forum acknowledged the need for urgent and immediate actions against the threats and challenges of climate change.
Forum chair and Tuvalu Prime Minister, Kausea Natano, called for 'immediate action and not just discussion of ambition'.
"Five years on, we must now ask ourselves, 'are we making the necessary policy and behavioural change to keep us on the 1.5-degree pathway from the perspective of the Blue Pacific?'
"The answer is simple. No, we are not."
Natano said every effort must be made to address the impacts of climate change.
"As leaders of the Pacific Islands Forum (PIF), custodians of the world's largest ocean and carbon sink, and representatives of our Pacific peoples, we call for immediate action and not just discussion of ambition," the leaders said in a communiqué.
"Action must be taken in our region, and internationally, to support clean, healthy, and productive oceans, the sustainable management, use and conservation of marine resources, growth in the blue economy and address the impacts of climate change on ocean health."
Fiji, with a population of around 900,000, is one of the victims of climate change.
Since 1993, Fiji had recorded a six-millimetre increase in its sea level per year, higher than the global average and villages have been relocated as a result of rising sea levels.
According to its Climate Change Policy, global sea level changes would more than double by the end of the century.
Prime Minister Frank Bainimarama was among more than 30 leaders and dialogue partners who addressed Friday's summit.
Bainimarama said Fiji was the first country to ratify the Paris Agreement as well as the first small island state to lead the climate negotiations.
He said Fiji held the presidency of the 23rd Conference of the Parties to the United Nations Framework Convention on Climate Change (COP23).
"Now Fiji is among the nations committed to net-zero emissions by 2050," he said.
Bainimarama urged world leaders to act in the fight against climate change.
"We all signed the Paris Agreement. Now let's insist that we put it to work. I urge all world leaders to act. Act for all of us. Act for our future. Act for our children and grandchildren," he said.
He pointed out that five years on from the 2015 UN Climate Change Conference (COP21) and the Paris Agreement, the world was still warming at an astonishing rate.
"This is not just Fiji's climate emergency, it is the world's emergency ... We all depend on each other. Climate complacency by one will harm all others," said the prime minister.
He said more consistent and aggressive actions were needed across the world, and all nations should find ways to do more than they ever thought possible.
All parties must submit ambitious mid-century targets for achieving net-zero global emissions, he said.
Bainimarama said speeches would not save the world and neither would nice tweets or photo-opportunities, and that the only expectation was action.
"If we don't win the race to net-zero emissions, we are headed for 3 or 4 degrees of global warming - an Earth we will not recognize and a climate we cannot survive.
"From here on out, our only expectation is action. We need solidarity we can feel; reductions in emissions we can measure, and resources vulnerable nations can afford to access now," he said.
More than 30 leaders and dialogue partners took part in Friday's talks.
Bainimarama said world leaders must view post-pandemic recoveries through the lens of opportunity, "heed what the market is telling them, harness renewables, and return people to work in green and blue industries.
"Governments and the private sector must lead a transparent transition to a more climate-resilient financial sector."
Like Fiji, Samoa with a population of around 200,000, is also a victim of climate change.
Samoa's Prime Minister Tuila'epa Sa'ilele Malielegaoi told the summit no one country or a single group of nations, and no single organization could solely win the war against climate change, a 'societal problem requiring a decisive global response'.
Tuilaepa said united, the international community could do a great deal to arrest and even reverse the threat of climate change.
Friday's Pacific summit came ahead of the UN-brokered talks on the issue.
UN Secretary-General Antonio Guterres called on every country to declare a 'climate emergency' on Saturday as world leaders marked the Paris accord's anniversary.
Leaders made mostly incremental pledges relative to the scale of the crisis.
Guterres had been buoyed in recent months by renewed commitment from China and the prospect of US President-elect Joe Biden bringing the United States back into the pact.
But the leaders, dozens of them, mostly offered tweaks to existing commitments or promises of bolder moves before crucial talks in Glasgow in late 2021.
This, the UN chief said, was no breakthrough to new policies to hasten the end of fossil fuels.
"Can anybody still deny that we are facing a dramatic emergency?Guterres, a former Portuguese prime minister who had made climate change his signature issue, told the virtual meeting.
"That is why today, I call on all leaders worldwide to declare a State of Climate Emergency in their countries until carbon neutrality is reached."
"With the impacts of climate change increasingly stark since the Paris deal was struck - ranging from wildfires in Australia and California to collapsing ice sheets - popular pressure has grown on leaders to listen to warnings from scientists."
Britain announced it would stop direct government support for overseas fossil fuel projects.
Campaigners hailed the move for putting pressure on other G7 economies to restrict support for oil and gas companies, reeling from the impact of Covid-19.
Pledges to back Paris from India, Germany and France were welcomed less in terms of substance and more for keeping alive hopes of faster action to meet the monumental challenge of halving global emissions by 2030 in line with the Paris pact.