An analytical solution to the boundary‐value problem for the existence of a Bleustein–Gulyaev piezoelectric surface acoustic wave in GaAs and other piezoelectric cubic crystals is presented. Numerical solutions for Bleustein–Gulyaev waves in a number of crystals of 4¯3mand 23 symmetry classes are also presented. These include commonly used materials such as GaAs, GaP, InSb, InAs, Bi12GeO20, and Bi4Ge3O12. The results are then used to investigate light diffraction by Bleustein–Gulyaev waves in GaAs. Both plane‐wave acousto‐optic and guided‐optical‐wave interaction cases are considered. Numerical solution for a guided‐wave acousto‐optic collinear interaction in a GaAs‐GaAlAs waveguide is presented and discussed. In addition, a simple method of Bleustein–Gulyaev wave detection using optical techniques is developed and illustrated through numerical calculations.