Photosensor array gesture detection techniques are described. In one or more embodiments, a computing device includes an array of photosensors. The photosensor array can be configured in various ways to measure changes in the amount of light that occur based upon a user's hand position above the photosensor array. In at least some embodiments, capacitance associated with the photosensors is charged and data regarding discharge rates for the sensors is collected that is indicative of the amount of incident light. Sequential changes in the amount of light that is measured across the array of photosensors can be used to determine positioning and/or movement of the user's hand in three dimensions (e.g., track position/motion in three-dimensional (3D) space relative to the computing device.) Accordingly, various gestures can be defined in terms of input obtained via the photosensor array and recognized to trigger corresponding operations by the computing device.