Public debt plays a crucial role in the economic development of many countries, the effective management and servicing of the external public debt have become a priority in the financial and economic policy of the state, ensuring the stability of its development. The article aims to develop Ukraine’s external public debt management system during the wartime. As a result of the analysis, the key negative consequences of the impact of external debt growth on Ukraine`s economic security were determined, i.e. economic growth slowdown, increased dependence on creditors, increased costs of the public debt servicing, significant reduction in domestic consumption, etc. The developed external public debt management system in the framework of state economic and financial security includes relevant subsystems, principles, functions, objects and subjects, methods. It was substantiated that the appropriate external public debt management system during wartime in Ukraine requires the following additional subsystems: subsystem of crisis planning and response, subsystem of external debt settlement and subsystem for ensuring international cooperation.