Evidence of the habitability of nearby exoplanets could be found with future space missions using the technique of nulling interferometry. A nulling interferometer selectively suppresses the glare of starlight while allowing the light from planets to be detected. Here we report the first demonstrations of broadband mid-infrared nulling at the level required to enable such a space mission. In three separate 6 hr measurements, mid-infrared nulls were demonstrated at a mean level less than1.0 × 10-5 1.0 × 10 - 5 using a 34% bandwidth centered at a wavelength of 10 μm. This was accomplished by “adaptive nulling,” in which a deformable mirror is tuned to minimize wavelength-dependent phase and intensity differences in the interferometer.