Electroadhesion (EA) is the phenomenon of surface adhesion caused by electrostatic attraction due to electric fields, whether externally applied or originating from quasi-permanent surface charges (i.e., passive EA). In our study, the adhesion force is provided by the charges stored in the electret polyethylene terephthalate (PET) film. This study provides a clear and quantitative understanding of how a PET electret film behaves as a passive electroadhesive material. The tested film is charged via direct-current corona discharge (point-plane electrode configuration, ±10 kV) to impart a quasi-permanent surface charge. Key charge-storage characteristics (including surface potential distribution and charge decay time) are measured. This characterization revealed a non-uniform (bell-shaped) surface potential profile and long charge storage time on the PET film (t95% > 980 s). Next, the electrostatic adhesion force between the charged film and a grounded conductive surface is quantified at various film-surface separations (0.5 mm to tens of millimeters) using a precision force measurement setup. The attractive force increases with the film’s surface charge and decreases steeply with increasing separation distance, reaching approximately 16.6 mN at a 0.5 mm separation (corresponding to a surface charge density of about 4.2 mC/m²). These results demonstrate the feasibility of corona-charged PET as a low-power electroadhesive material.