A protective gasket for a display module of a portable electronic device and a method for assembling the device. The electronic device includes a housing frame, a main body having a display module, and a flexible gasket between the frame and main body, the frame having a display window corresponding to the display module. A cut is at corner portions of the gasket so that inner edges of the flexible gasket are bent after the display module is embedded into the display window, and then compressed and fitted between the outer periphery of the display module and the inner periphery of the display window. With the inner edges of the flexible gasket bent, the thickness of the electronic device can be reduced, and the periphery of the display module can be protected. The display module also can be protected from intrusion by foreign matters such as dust and moisture.