A novel 4-D gesture sensing technique using reconfigurable virtual array method with a 60-GHz frequency-modulated continuous wave (FMCW) radar is presented. The 4-D sensing includes the 3-D spatial positioning and the 1-D motion tracking, which combines detection in both spatial and temporal domains. The proposed technique can be used for gesture sensing for both macro gestures such as handwriting letters and numbers, hand drawing different patterns in space and micro gestures such as the fingers' actions of virtual slider, finger tap, and finger wave. Moreover, this work presents a method to reconfigure the working modes of different transmitting and receiving channels in the multiple input and multiple output (MIMO) architecture, which effectively increases the sensing range of the radar sensor and the signal-to-noise ratio (SNR) of the beat signal. For various gestures at different distances or in different environments, the proposed technique can adaptively achieve the best detection by reconstructing the virtual array of the MIMO radar. A series of experiments are carried out in both microwave anechoic chamber and office environments to validate the proposed technique. The experimental results show that the proposed technique performs well in sensing a variety of both macro gestures andmillimeter-level micro gestures. Compared with the conventional MIMO method, the proposed technique increases the sensing range by 3.5 times, and the SNR is also greatly improved by 12 dB when the radar performs gesture sensing at the distance of 0.65 m.