The development of thin, dense, defect-free solid electrolyte films is key for achieving practical and commercially viable solid-state batteries. Herein, we showcase a facile processing pathway for antiperovskite (Li2OHCl) solid electrolyte materials that can yield films/pellets with very high densities (∼100%) and higher conductivities compared with conventional uniaxially pressed pellets. We have also achieved close to 50% improvement in the critical current density of the material and an improved lithiophilicity due to the surface nitrogen enrichment of the processed pellets. Distribution of relaxation time analysis supports the contributions from “faster” transport mechanisms for the antiperovskite films/pellets developed using the new protocol. Overall, the results highlight the feasibility of our new processing pathway for engineering antiperovskite solid electrolytes at the grain scale as a highly desirable approach for practical all-solid-state batteries.