<p>Perovskites have attracted widespread attention for laser applications due to their excellent optoelectronic properties. However, perovskite lasers typically exhibit a wavelength shift as pump density increases. Here, we report a pump-induced wavelength shift-free laser achieved using a perovskite nanoplatelet with mixed orthorhombic and tetragonal phase. At 293 K, the tetragonal-phase perovskite nanoplatelet laser exhibits a blue shift of ~0.4 nm µJ⁻¹ cm² with increasing pump density. In contrast, at 80 K, the orthorhombic-phase perovskite nanoplatelet laser exhibits a red shift of ~1 nm µJ⁻¹ cm². By stabilizing the perovskite nanoplatelet in a mixed orthorhombic-tetragonal phase at 163 K, the pump induced wavelength shifts are completely suppressed, resulting in a wavelength-stable laser. Additionally, the lasing threshold decreases from 18.4 µJ cm⁻² at room temperature to 4.5 µJ cm⁻² at 163 K. This study presents a promising strategy for achieving pump-insensitive wavelength stability in micro/nano lasers.</p>