Organic photodetectors (OPDs) offer molecular tunability and solution processability, yet their direct integration into photonic integrated circuits (PICs) remains largely unexplored. PICs route and process optical signals on-chip using sub-micrometer waveguides for communication and sensing. Here, we present a plasmonic nanogap OPD with coplanar electrodes, in which a bulk heterojunction is infiltrated into a nanoscale channel. The nanogap electrodes are fabricated using adhesion lithography, enabling scalable large-area patterning in a 32 × 32 array format. The device exhibits a strong near-infrared photoresponse with high-performance photodetection in an extremely confined active area, originating from plasmonic field enhancement and trap-assisted photomultiplication. Furthermore, a polymer waveguide is patterned above the nanogap, enabling guided-light detection. These results demonstrate plasmonic nanogap OPDs as waveguide-integrated detectors for on-chip photonic systems.