An image sensor device may include an interconnect layer, an image sensor IC carried by the interconnect layer and having an image sensing surface, and encapsulation material laterally surrounding the image sensor IC and covering an upper surface of the image sensor IC up to the image sensing surface. The image sensor device may include an optical plate having a peripheral lower surface carried by an upper surface of the encapsulation material and aligned with the image sensing surface, the optical plate being spaced above the image sensing surface to define an internal cavity, and a lens assembly coupled to the encapsulation material and aligned with the image sensing surface.