A variable core cowl vent nozzle system is described herein, the system including a core casing at least partially surrounding a core engine of a gas turbine engine, and a core cowl extending aftward from the core casing. The core cowl defines a core cowl vent area between the core cowl and a primary nozzle. At least one of the core cowl and the primary nozzle is movable to vary the core cowl vent area. A method for varying the core cowl vent area by moving one or more of the core cowl and the primary nozzle is also described herein.