The imperative for ammonia sensors to exhibit high selectivity and sensitivity, capable of detecting low ppm levels, is paramount for addressing toxicity risks, industrial hazards, and medical concerns. Nevertheless, MXene-based sensors often encounter performance constraints owing to residual Al impurities from the MAX (Ti₃AlC₂) phase, which hinder charge transport and surface reactivity. In this study, we developed a high-performance Ti₃C₂T_x/ZnO hybrid sensor through an innovative LiF–HCl-assisted Minimally Intensive Layer Delamination (MILD) etching method, eliminating the need for hazardous HF. Optimization of the LiF concentration significantly enhanced surface functionalization, resulting in high-purity, fully delaminated Ti₃C₂T_x nanosheets with abundant active sites for gas adsorption and redox reactions. A Ti₃C₂T_x/ZnO hybrid composite was produced via DC reactive magnetron sputtering and drop-casting, establishing a Schottky junction to promote charge transfer. The resultant L3-Ti₃C₂T_x/ZnO sensor demonstrated a 50-fold enhancement in NH₃ sensitivity, a 4.5-fold acceleration in response at 5 ppm compared to pristine ZnO, and an ultra-low detection threshold of 0.1 ppm (4.52 ± 1.1). It exhibited rapid response (44 s) and recovery (26 s) times, high selectivity, remarkable stability over 60 days, and resilience to humidity fluctuations at 300 K. The exceptional performance of the sensor was ascribed to the synergistic effect, enhanced charge perturbation, expedited adsorption–desorption kinetics, and surface redox interactions at the interface. The proposed L3-Ti₃C₂T_x/ZnO hybrid Schottky junction represents a significant advancement in hazardous gas monitoring, industrial safety, and environmental protection applications.