We first demonstrate the laser performance of a Cr2+:CdSe passively Q-switched (PQS) 2.09 μm Ho: YAG laser resonantly pumped by a thulium-doped fiber laser. The maximum output pulse energy of 1.766 mJ, corresponding to a repetition frequency of 685 Hz, was obtained with a pulse duration of 15.4 ns. The pulse peak power was 114.7 kW, while the PQS efficiency was 21.45% against the continuous-wave output. The laser wavelength in the PQS operation was precisely measured to be 2090.2 nm.