Quantum action‐angle variables are used to describe and analyze a number of familiar systems. For a given system, the quantum canonical transformation from the old coordinates, e.g., linear or polar, to the new coordinates, action‐angle variables, is found by generalizing the corresponding classical transformation using a method based upon the correspondence principle, the Hermiticity and canonical nature of the old coordinates, and the requirement that the Hamiltonian be independent of the quantum angle variable. The bound‐state energy levels and other important system properties follow immediately from the canonical transformation. Harmonic oscillators of various dimensions and the three‐dimensional angular momentum system are used as illustrations; these illustrations provide interesting alternatives to the usual quantum treatments.