The initiative, spearheaded by the Minderoo Foundation and Global Fishing Watch, was announced at a global ocean summit in Kenya on Thursday.
Combining satellite imagery and vessel tracking data, the map will provide a near-real-time snapshot of millions of fishing vessels.
"This is genuinely uncharted territory," Minderoo Foundation founder Andrew Forrest said.
"No one has attempted to map global fishing effort at this scale before."
The map, due for release within two years, is designed to curb overfishing by helping policymakers and fisheries track fishing activity worldwide.
Global Fishing Watch currently tracks the activity of more than 100,000 large and medium-sized fishing vessels through its open-access map.
The updated map will leverage satellite imagery and machine learning to bring online millions of previously invisible smaller vessels.
GFW chief scientist David Kroodsma told AAP likened the development to extending Google Maps to fishing activity on the open seas.
"Anywhere on land in the world, you can see where the buildings are, you can see what's happening," he said.
"As soon as you go over the ocean, it turns into pixelated nothingness."
It will also give a more comprehensive view of fishing activities by all boats and allow users to break vessels down by size.
Australian Marine Conservation Society sustainable fisheries manager Adrien Meder said vessel size was a key part of the conservation puzzle.
"Smaller artisanal fishing boats, massive industrial tuna vessels or factory freezer trawlers essentially all look the same out there," Mr Meder said.
The map will also shed new light on so-called "dark fleet" operators, using optical imagery to pinpoint unregistered vessels to a new level of detail.
These are vessels that do not transmit their location, sometimes engaging in illegal and unreported fishing, at times with devastating consequences.
About three-quarters of the world's industrial fishing vessels are not publicly tracked, according to a study led by Global Fishing Watch.
The study, published in Nature, relied on data from 2017 to 2021 and found untracked operations mostly occurred near South Asia, Southeast Asia and Africa.
"There are vast fleets out there fishing in the high seas," Mr Meder said.
"They're causing absolutely catastrophic overfishing."
While Australia has relatively strict oversight of its waters, Mr Meder said illegally caught produce often finds its way into domestic food chains.
"Without visibility of what these boats are doing at every stage, we lose that traceability from our plate back to the ocean," he said.
Minderoo Foundation was co-founded by Dr Forrest, founder and executive chairman of mining company Fortescue, and Nicola Forrest in 2001.
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