We reported a cascade gaseous stimulated Raman scattering (SRS) laser for efficient generation of 2.6 μm mid-infrared radiation. The system employed two sequential seven-pass cells. A 1064 nm Nd:YAG pump laser was first converted to 1907 nm first-Stokes radiation in a H2-filled cell. This output then served as the pump for a second cell filled with CO2, generating the final output at 2594 nm. This dual-cell configuration effectively extended the wavelength to the targeted spectral region. Optimized operation with 0.20 MPa H2 and 0.3 MPa CO2 yielded a 21.6 mJ 2594 nm laser from 124 mJ of 1907 nm pump energy, corresponding to a PCE of 23.7% and peak power of 2.63 MW. The beam quality factor (M2) of the 2594 nm output was measured to be 2.46. This work presents an effective technical route for producing high-peak-power MIR lasers.