Outflow valve (OFV) assemblies including non-metallic frames and enhanced attachment features are provided. In embodiments, the OFV assembly includes a non-metallic frame to which at least one valve door is pivotally mounted. The non-metallic frame may, in turn, include a generally rectangular frame body, a central opening through the frame body, an outer peripheral flange extending around at least a portion of the frame body. Frame attachment interfaces are distributed or spaced around the outer peripheral flange of the non-metallic frame. The frame attachment interfaces include fastener openings and elevated platform regions, which project from an inboard side of the outer peripheral flange and through which the fastener openings extend. Base plates seat against the elevated platform regions. Fasteners engage the base plates and extend through the fastener openings to an outboard side of the outer peripheral flange to attach the OFV assembly to an aircraft fuselage.