We investigate the gravitational effect on Landau levels. We show that the familiar infinite Landau degeneracy of the energy levels of a quantum particle moving inside a uniform and constant magnetic field is removed by the interaction of the particle with a gravitational field. First, two independent approaches are used to solve the relevant Schrödinger equation. It is found that both approaches yield qualitatively similar results within their respective approximations. Then, with the goal of clarifying some confusing results found in the literature concerning the use of a third independent approach for extracting the quantization condition based on a similar differential equation, we show that such an approach cannot yield a general and yet consistent result. We point out to the more accurate, and yet impractical, way to use such an approach, a way which does in principle yield a consistent quantization condition.Finally, we show how our results could be used to contribute in a novel way to the existing methods for testing gravity at the tabletop experiments level as well as at the astrophysical observational level.