Abstract In recent years, metal halide perovskite nanocrystals (NCs) have been favored by many researchers due to their unique properties including long carrier diffusion length, high carrier mobility, tunable emission wavelength, and narrow full width at half maximum, making them great application potentials in optoelectronic devices. The photoluminescence quantum yields of perovskite NCs are nearly 100%, and the device efficiency of perovskite NC‐based light‐emitting diodes (LEDs) has been improved significantly from below 0.1% to over 20%. In addition, perovskite NC‐based solar cells and photodetectors have also developed rapidly in recent years. Here, we summarize the synthesis and the basic optoelectronic properties of metal halide perovskite NCs and introduce their applications in LEDs, solar cells, and photodetectors.