We present here a scanning photocurrent microscopy study of individual graphene nanoribbons, revealing pronounced photocurrent responses close to the nanoribbon/metal contacts. The magnitude of the corresponding photocurrent signal was found to be directly proportional to the conductance of the devices, suggesting that a local voltage source is generated at the nanoribbon/metal interface by the photo-thermoelectric Seebeck effect. The dominance of this mechanism is attributed to the reduced thermal conduction capability of the nanoribbons in comparison to extended graphene sheets. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4789850]