A new multiwavelength transverse‐junction‐stripe (MW‐TJS) laser is developed and demonstrated. Such MW‐TJS laser is capable of emitting multiple predominantly single–longitudinal mode emissions having preselected lasing wavelengths. The wavelengths of the lasing lines, their separations, and the number of lasing lines obtainable from a single MW‐TJS laser can be predetermined. In this experiment, the MW‐TJS lasers were grown by molecular beam epitaxy (MBE). As an example, four different lasing lines at 9025, 8793, 8532 and 8276 Å were obtained simultaneously from a single 4‐wavelength TJS laser. The pulsed and cw current thresholds Ith for such 4‐wavelength TJS laser with cavity length of 375 μm and each active layer thickness of 0.5 μm are 245 and 252 mA, respectively. In the case of regular TJS lasers grown by MBE, the pulsed and cw Ith’s are 37–50 and 40–54 mA, respectively.