The M7.8 Haida Gwaii earthquake occurred off the coast of the Haida Gwaii archipelago (British Columbia, Canada) on October 28, 2012. It generated up to 13 m tsunami waves and 3 m run-up over the ∼200 km coastline. Fortunately, damages from the earthquake and tsunami were minor due to the lack of vulnerable infrastructure in this remote area. The earthquake epicentre was located at the margin, where the Pacific and North American plates undergo oblique convergence. Various finite fault models of the earthquake have been previously computed from seismic and GNSS data from two continuous and five campaign stations was used for model validation. Yet, the uncertainty in the fault location and slip distribution remained high because of the poor distribution of seismic and GNSS stations near the epicentre. In this study, a rectangular source model and two finite fault models, with uniform and resolution-based patch sizes, were derived from three recomputed using the precise orbital state vectors RADARSAT-2 interferograms and previously published GNSS data. These models define the location of the fault and provide detailed slip distribution with a high degree of certainty. In addition to coseismic deformation, the interferograms captured a part of postseismic deformation, so the estimated moment magnitude (Mw) of 7.91-7.93 is slightly larger than ∼7.8, the previously reported moment magnitude of this earthquake. The study provides an improved finite fault slip model and demonstrates the benefits of Synthetic Aperture Radar data for measuring coseismic deformation in remote areas where ground-based measurements are sparse.