The conference took place amid heightened tensions across the border after North Korea recently sent hundreds of balloons carrying garbage to the South, which raised alarms about the potential danger of unmanned flying vehicle attacks from Pyongyang.
The forum focused on cooperation among civilian sectors, the government and the military in establishing a system to defend against drone attacks.
It is the third time that the city government has hosted a security conference with the military, following two sessions held last year.
Participants included Mayor of Seoul Oh Se-hoon, Commissioner of the Seoul Metropolitan Police Agency Jo Ji-ho, and Commander of the Capital Defense Command Lee Jin-woo.