Near-infrared (NIR) solid-state micro/nanolasers are important building blocks for true integration of optoelectronic circuitry.1 Although significant progress has been made in III-V nanowire lasers with achieving NIR lasing at the room-temperature,2-4 challenges remain including low quantum efficiencies and high Auger losses. Importantly, the obstacles towards integrating 1-D nanowires on the planar ubiquitous Si platform need to be effectively tackled. Here we demonstrate a new family of planar room-temperature NIR nanolasers based on organic-inorganic perovskite CH3NH3PbI2X (X= I, Br, Cl) nanoplatelets. Their large exciton binding energies, long diffusion lengths and naturally formed high-quality planar whispering-gallery mode cavities ensure adequate gain and efficient optical feedback for low-threshold optically pumped in-plane lasing. We show that these remarkable wavelength tunable whispering-gallery nanolasers can be easily integrated onto conductive platforms (Si, Au and indium tin oxide, etc). Our findings open up a new class of wavelength tunable planar nanomaterials potentially suitable for on-chip integration.