The probe will investigate 25 strikes in Pakistan, Yemen, Somalia, Afghanistan, and the Palestinian territories. It also will focus on civilian killings and injuries caused by the strikes.
British lawyer Ben Emmerson, the U.N. special envoy on counterterrorism and human rights, will carry out the probe.
Emmerson says the use of drone technology is "here to it stay," adding it is imperative that "appropriate legal and operational structures are urgently put in place to regulate its use."
Most attacks by unmanned drones have been carried out by the United States. Israel has used them and other nations have access to the technology.
Pakistan was one of three countries that requested the investigation, condemning U.S. drone strikes on targets along its border with Afghanistan. Pakistan says the strikes not only violate its sovereignty, but that collateral damage is fueling militancy in the region.
Meanwhile, the U.N. Security Council Thursday approved the use of unmanned surveillance drones over eastern Congo to monitor militias. The council said the drones would be deployed on what it calls a "case by case" basis.
Last month, Secretary-General Ban Ki-moon asked the Council to consider using unmanned aerial systems to permit timely decision-making in dealing with M23 rebels in eastern Congo.