We report on a miniature Yb:LuPO4 crystal laser at 1.01 μm that is passively Q-switched with a sapphire-based few-layer WS2 saturable absorber, and that can be operated under very high output couplings (≥80%). With 12.6 W of pump power absorbed, an average output power of 4.35 W is generated at a repetition rate of 1.33 MHz with a slope efficiency of 47%. The maximum pulse energy and highest peak power achieved are 3.41 μJ and 110 W, respectively; while the shortest pulse duration obtained is 28.6 ns. To the best of our knowledge, these results represent the highest output power and shortest pulse duration ever achieved in the 1 μm region from solid-state lasers passively Q-switched by using two-dimensional saturable absorbers.