A harness apparatus for use with a head-mounted display device is disclosed. In at least one embodiment, the apparatus provides a pair of display connector portions positioned on opposing left and right sides of the display device. A harness assembly provides at least one elongate primary head strap for engagement about a user's head, with opposing terminal ends of the at least one primary head strap being positioned proximal a left temple and a right temple, respectively, of the user's head, and providing a pair of strap connector portions configured for removable engagement with the pair of display connector portions. The harness assembly further provides a gasket extending between the strap connector portions and configured for being positionable in contact with a face of the user so as to be sandwiched between the display device and the user's face when the display device is engaged with the harness assembly.