Bacillus velezensis KHH13 (KHH13), a proven plant growth promoter, has been commercialized for agricultural use. We developed a heat tolerance-enhancing KHH13 formulation (HA+KHH13) and its production technology. In greenhouse cucumber trials under high-temperature stress, HA+KHH13 reduced plant wilting by 66% and increased biomass by 15.38% compared to the control. Summer field trials demonstrated a 19.21% increase in marketable fruit rate and a 3.3 ton per hectare yield increase with KHH13-HA.