Abstract <p>The optical properties of a GaAs quantum wire subjected to external electric and magnetic fields are theoretically investigated within the effective-mass approximation. The combined influence of crossed electric and magnetic fields on intersubband and interband optical absorption is analyzed with particular emphasis on room-temperature operation. The results reveal that the magnetic field significantly enhances the lateral confinement, leading to pronounced blue-shifts of the optical transition energies for both intersubband and interband processes. In contrast, the electric field mainly affects the absorption intensities through wave-function displacement and modulation of electron–hole overlap, while exerting only a weak influence on the transition energies. The magnetic-field-induced tunability is shown to remain robust at <i>T</i> = 300 K, despite phonon-induced spectral broadening. These findings demonstrate that GaAs quantum wires offer a high degree of controllability under external fields and represent promising candidates for tunable infrared and magneto-optoelectronic applications.</p>