We investigate the complex rupture properties of the 2016 7.8 Kaikōura earthquake by jointly inverting teleseismic body‐wave and regional Global Positioning System (GPS) coseismic deformation data within a multifault model. We validate our results by forward modeling recorded Interferometric Synthetic Aperture Radar (InSAR) interferograms. Our study reveals the complementary depth‐dependent contributions of teleseismic and local geodetic data to the cumulative slip distribution. The resulting joint inversion model of the rupture process and slip pattern explains both the far‐field (teleseismic data) and near‐field (GPS and InSAR data) observations. The model highlights variable rupture velocity throughout the sequence, with an initial high‐velocity () pulse followed by slow () yet significant reverse and transverse motion on faults stretching at least 160 km to the north of the origin. We map significant thrust motion on a dipping plane representing the combined effects of the Hope, Hundalee, and Jordan thrust faults as well as large strike‐slip motion along the Kekerengu and Needles faults. The mainshock also ruptured the deep portion of the subduction interface at a velocity of .