A simple, practical method is described to extract the carrier concentration and mobility of each component of a multicarrier semiconductor system (which may be either a homogeneous or multilayered structure) from variable magnetic field measurements. Advantages of the present method are mainly due to the inclusion of both the longitudinal and transverse components of the conductivity tensor and normalization of these quantities with respect to the zero‐field longitudinal component of the conductivity tensor. This method also provides a simple, direct criterion by which one can easily determine whether the material under test is associated with a one‐carrier or multicarrier conduction. The method is demonstrated for a simple one‐carrier system [GaAs single‐channel high‐electron‐mobility‐transistor (HEMT) structure] and two multicarrier systems (an InGaAs‐GaAs double‐channel HEMT structure and two types of carriers present in an InGaAs single‐channel HEMT structure). The analysis of the experimental data obtained on these samples demonstrates the utility of the method presented here for extracting carrier concentrations and mobilities in advanced semiconductor structures.