In this paper, we report on high-power stable nanosecond pulse generation at ~2.1 μm from an integrated Tm-Ho all-fiber master oscillator power amplifier (MOPA) system. A total output power of 128.5 W is generated from the Tm-Ho hybrid MOPA, with an average power of 99.1 W from Ho emission at 2116 nm; the corresponding pulse repetition frequency and pulse width are 161 kHz and 322 ns, respectively, leading to a peak power of 1.91 kW. The Tm-Ho integrated master oscillator is designed to operate at 1980 and 2116 nm, where the former wavelength serves as the pump of the Ho-doped fiber. Stable laser pulses are generated from both the Tm and Ho oscillators owing to mutual modulation of emission from the two lasers. The prospects for further scaling in output power at ~2.1 μm using Tm-Ho integrated MOPA system are discussed.