MLAs have called for a stop to the practice of gas exploration known as fracking.
They backed a call for a moratorium on onshore and offshore exploration and the withdrawal of licences by 49 votes to 30.
However, Enterprise Minister Arlene Foster said the motion was flawed as no licences for fracking had been issued.
It is not clear if the vote will have any effect on how the executive now decides to proceed.
Earlier on Tuesday, the debate was temporarily suspended while an anti-capitalist protester was removed from the public gallery by police.
Fracking, also known as hydraulic fracturing, is a process of drilling down and creating tiny explosions to shatter and crack hard shale rocks to release the gas inside.
Gas could potentially be extracted in Fermanagh in the future by this controversial process.
Water, sand and chemicals are injected into the rock at high pressure which allows the gas to flow out to the head of the well.
There are concerns that potentially carcinogenic chemicals can sometimes escape and find their way into drinking water sources.