Countries have agreed to strengthen protections for 18 threatened species of sharks and rays, including those hunted for their meat and fins.
The proposal was passed at the Convention on International Trade in Endangered Species (CITES) on Sunday.
The newly protected species include mako sharks, wedgefishes and guitarfishes.
A demand for shark fin soup is one of the driving factors in the depleting numbers of sharks in the ocean.
The proposal, which was tabled by Mexico and requires ratification this week, means that the species can no longer be traded unless it can be proven that their fishing will not impact the possibility of their survival.
The number of sharks killed each year in commercial fisheries is estimated at 100 million, with a range between 63 million and 273 million, according to The Pew Trust.
Makos, the fastest shark species, have almost disappeared completely from the Mediterranean and numbers are diminishing rapidly in the Atlantic, Northern Pacific and Indian oceans.
Although 102 countries voted in favour of the move, 40 - including China, Iceland, Japan, Malaysia and New Zealand - opposed it.
Some argued that there was not enough evidence to show that mako sharks were disappearing as a result of fishing.
Sharks and rays: The facts on the "rhinos of the seas"
- A group of 16 very unusual animals called wedgefish and guitarfish, together known as rhino rays
- They are assessed as the most threatened family of marine fish - all bar one is critically endangered
- Two of the wedgefish species may already have been driven to extinction by commercial fisheries
- Wedgefish have two large dorsal fins and a large tail lobe, prized for use in soup.
Ali Hood, director of conservation at Shark Trust, welcomed the move.
"Mako are highly valued for their meat and fins. Decades of unrestricted overfishing, particularly on the high seas, has led to significant population declines," Ms Hood told the BBC.
The "listing would be critical for ensuring that international trade is held to sustainable levels, prompting urgently needed catch limits and improving traceability", she added.