The uncontrolled eruption of Sidoarjo mud since 2006 triggered by gas exploration drilling has created one of Indonesia's most severe environmental disasters, discharging millions of cubic meters of volcanic mud annually and threatening surrounding communities. Simultaneously, LPG fire hazards demand effective, sustainable extinguishing agents. This study presents the first valorization of Sidoarjo mud waste into a high-performance fire suppressant through controlled SiO₂ modification (0–20 wt%). The mud was characterized for crystallinity (XRD), thermal stability (TGA-DTA-DTG), and fire suppression performance against LPG flames, with optimization via response surface methodology (RSM). Results demonstrate that SiO₂ incorporation preserves native mineral phases while significantly enhancing crystallinity (+23.6% at 20 wt% SiO₂) and thermal stability reducing total mass loss by 32% up to 1000 °C, with 53.9% reduction in the critical 350–500 °C region relevant to LPG flame temperatures. Extinguishing time decreased inversely with SiO₂ content, reaching 0.12 s at 20 wt% SiO₂ (70% faster than unmodified mud). RSM optimization identified optimal formulation at 18.625 wt% SiO₂ and 0.84 g/cm² powder mass-to-flame-area ratio, achieving an ultra-fast extinguishing time of 0.142 experimentally validated with 1.4% error. Mechanistically, enhanced performance arises from synergistic coupling of thermal buffering (enhanced by improved crystallinity), oxygen barrier formation (optimized by powder loading), and flame destabilization.