We report a high-energy single-frequency deep-ultraviolet (DUV) solid-state laser at 167.079 nm by the eighth-harmonic generation of a diode-pumped Nd:LGGG laser. A maximum DUV laser output energy of 1.5 μJ at a 5 Hz repetition rate with a 200 μs pulse duration is achieved. The central wavelength of the DUV laser is located at 167.079 nm and can be finely tuned from 167.075 to 167.083 nm. The linewidth is estimated to be 0.025 pm. To the best of our knowledge, this is the first Letter reporting a high-energy single-frequency solid-state DUV laser below 170 nm. The successful demonstration of the high-energy single-frequency DUV laser source with the unique wavelength is useful for direct detection of a Al+27 ion via resonance fluorescence in a multi-ion optical clock.