Significance The performances of devices based on transition metal dichalcogenides (TMDs) are far from their intrinsic limits, presumably due to various disorders in these 2D crystals. To date, little is known about the magnitude and characteristic length scale of electrical inhomogeneity induced by the disorders in TMDs. In this paper, strong mesoscopic (submicrometer) electrical inhomogeneity in MoS ₂ flakes, which reveals the potential fluctuations, was observed by a unique technique termed microwave impedance microscopy. The local conductance of edge states and its contribution to the transport were also resolved and analyzed experimentally for the first time, to our knowledge. The results provide a comprehensive understanding of the potential landscape in TMDs, which is very important for the improvement of device performance.