Developing new saturable absorbers for use in the mid-infrared region has practical significance for short-pulsed lasers and related scientific and industrial applications. The performance of gold nanorods (GNRs) as saturable absorbers at novel mid-infrared wavelengths needs to be evaluated even though these benefit from ultrafast nonlinear responses and broadband saturable absorption. Passive Q-switching of an LD-pumped 2.3 μm Tm:YLF laser using GNRs was successfully realized in this study. Pulses with an 843 ns pulse width and a 6.67 kHz repetition rate were achieved using this Q-switched laser. Results showed that GNRs provide promising passive Q-switches for 2.3 μm Tm-doped lasers.