Room temperature-operable mid-infrared (MIR) photodetectors have drawn significant attention due to their potential applications in imaging, security and sensing. The unique and tunable optoelectronic properties of graphene make it an attractive platform for designing tunable and broadband photodetectors. This work demonstrates a tunable mid-infrared photodetector using Graphene Nanoribbons (GNR) operated in the 5 - 12 µm range. We used the tunable plasmonic properties of graphene nanoribbons to model the photodetector. We numerically compute the generation rate using the plasmon-enhanced optical absorption in the GNR. We show a peak extinction of ~35% in the structure with GNR of width 50 nm and Fermi energy 0.3 eV is due to plasmonic resonances. The computed generation rate determines the photoresponse current in the GNR-based FET. The proposed structure shows a ~ 40-fold improvement in the peak photoresponse current in patterned structure over unpatterned structure in the wavelength 5 - 12 µm. Hence the tunable plasmonic resonances and the width dependent bandgap of GNRs enable the realization of room-temperature operable broadband MIR photodetector. © 2022 SPIE.