Nulling interferometry is a technique for darkening the field generated by a star relative to its surroundings by destructive interference. We describe a nulling interferometer incorporating a single beam-splitter (BS) cube. The device resembles a two-arm interferometer in which the arms are together in one collimated beam, and the two beam halves interfere with the help of the BS cube. By introducing an extra π/2 -phase difference between the two beam halves, it is possible to achieve destructive interference of the star with itself, while the off-axis image of the planet remains unchanged. An experimental setup is constructed to demonstrate the nulling features of this interferometer. A star and a planet solar system are simulated to prove its performance.