We demonstrate a 968 nm diode end-pumped Er,Pr:GYSGG (Gd₁.₁₇Y₁.₈₃Sc₂Ga₃O₁₂) laser at 2.79 μm operated in the pulse and continuous-wave (CW) modes. The lifetimes for the upper laser level ⁴I₁₁/ ₂ and lower level ⁴I₁₃/₂ are 0.52 and 0.60 ms, respectively. The laser produces 284 mW of power in the CW mode, corresponding to the optical-to-optical efficiency of 14.8% and slope efficiency of 17.4%. The maximum laser energy achieved is 2.4 mJ at a repetition rate of 50 Hz and pulse duration of 0.5 ms, corresponding to a peak power of 4.8 W and slope efficiency of 18.3%. These results suggest that doping deactivator Pr3+ ions can effectively decrease the lower-level lifetime and improve the laser efficiency.