The Chemical Weapons Convention (CWC), officially the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction, is an arms control treaty administered by the Organisation for the Prohibition of Chemical Weapons (OPCW), an intergovernmental organization based in The Hague, The Netherlands. The treaty entered into force on 29 April 1997, and prohibits the large-scale use, development, production, stockpiling and transfer of chemical weapons and their precursors, except for very limited purposes (research, medical, pharmaceutical or protective). The main obligation of member states under the convention is to effect this prohibition, as well as the destruction of all current chemical weapons. All destruction activities must take place under OPCW verification.

As of March 2021, 193 states have become parties to the CWC and accept its obligations. Israel has signed but not ratified the agreement, while three other UN member states (Egypt, North Korea and South Sudan) have neither signed nor acceded to the treaty. Most recently, the State of Palestine deposited its instrument of accession to the CWC on 17 May 2018. In September 2013, Syria acceded to the convention as part of an agreement for the destruction of Syria's chemical weapons.As of February 2021, 98.39% of the world's declared chemical weapons stockpiles had been destroyed. The convention has provisions for systematic evaluation of chemical production facilities, as well as for investigations of allegations of use and production of chemical weapons based on the intelligence of other state parties.

Some chemicals which have been used extensively in warfare but have numerous large-scale industrial uses (such as phosgene) are highly regulated; however, certain notable exceptions exist. Chlorine gas is highly toxic, but being a pure element and widely used for peaceful purposes, is not officially listed as a chemical weapon. Certain state-powers (e.g. the Assad regime of Syria) continue to regularly manufacture and implement such chemicals in combat munitions. Although these chemicals are not specifically listed as controlled by the CWC, the use of any toxic chemical as a weapon (when used to produce fatalities solely or mainly through its toxic action) is in-and-of itself forbidden by the treaty. Other chemicals, such as white phosphorus, are highly toxic but are legal under the CWC when they are used by military forces for reasons other than their toxicity.