OPEC has agreed to cut 1.2 million barrels a day from its output to 32.5 million barrels, effective in January.
Oil prices leaped 8% early Wednesday ahead of the decision, which curbs production for the first time in eight years.
The meeting of the Organization of the Petroleum Exporting Countries in Vienna comes amid a glut of global oil supply that has suppressed energy prices and increased tensions between members Saudi Arabia, Iran and Iraq.
As the meeting got underway OPEC Secretary General Mohammed Barkindo expressed optimism that a deal to limit supply and help struggling prices would be done.
U.S. benchmark crude added 6% to $47.97 a barrel in electronic trading on the New York Mercantile Exchange on Wednesday after falling 3.9% on Tuesday. Brent crude, used to price international oils, was up a similar amount in London.
OPEC production cuts tend to push up oil prices. However, the organization has chosen not to throttle production to try to maintain global market share and drive U.S. shale oil and non-OPEC gas producers, who have higher costs, out of business.
In June of 2014, oil traded at over $100 a barrel. OPEC last slashed production in 2008 as oil demand and prices slumped during the global financial crisis.
Saudi Arabia, which accounts for about a third of OPEC's output, is against any intervention to cut supply and has thwarted several attempts by the alliance's members to introduce cuts over the last year. But the Saudis' regional rival Iran favors a cut, in part so it can regain some of the market share it lost to Riyadh under years of sanctions from the West on its oil sales.
In the middle is Iraq, OPEC's second-largest producer, which wants a freeze in production. Iraq says it needs oil revenues to pay for its war against the Islamic State.
Saudi Arabia's Energy Minister Khalid al-Falih said Wednesday there was a "good chance" OPEC members would agree to restrain oil production.