This paper discusses the nonlinear optical properties of copper-containing potassium–aluminum–borate glass when it is acted on by a pulsed laser with wavelength 532 nm and pulse width 5 ns. It is shown that the nonlinear optical limiting threshold of the original copper-containing glass is 3×10−3 J, while that of glass with copper chloride nanocrystals is 5×10−6 J. It is shown that the maximum attenuation of a transmitted laser pulse with energy 0.05 J is a factor of 100 for the original glass with transmission 85%, while it is a factor of 1000 for glass with copper chloride nanocrystals and transmittance 70%. It is concluded that potassium–aluminum–borate glasses with copper chloride nanocrystals can be used as filter–limiters for the protection of the organs of vision and photodetectors from pulsed laser radiation.