In this letter, a high power, continuous-wave Tm:YAP InnoSlab laser has been developed. It produces 315 W of laser output power with an emission wavelength of 1.94 μm. The optical-to-optical efficiency and slope efficiency with respect to the absorbed pump power are 53.4% and 63.8%, respectively. At the output power of 300 W, the beam quality factors M
2 are 201 in the x-direction and 3 in the y-direction, respectively. The beam shape is rectangular, thus it is ideal for pumping a Ho:YLF laser crystal in InnoSlab design for oscillator and amplifier.