Underground mining environments pose significant safety risks due to the accumulation of toxic and explosive gases, necessitating the use of reliable and continuous monitoring systems. However, wired system configurations, complex maintenance, and incomplete spatial coverage have limited the implication of conventional methods, which hinder real-time data transmission during critical events, thereby increasing risks to miners and delaying emergency response. Herein, a ProGas-Mine System, a low-power, multi-node wireless sensor system, was developed to enable continuous and real-time monitoring of hazardous gases in underground mines, which can communicate over a long range. The proposed system integrates distributed sensor nodes equipped with gas sensors for methane (CH₄), carbon monoxide (CO), and hydrogen sulfide (H₂S), as well as temperature and humidity sensors. The incorporated Long Range (LoRa) wireless communication ensured reliable data transmission under challenging subterranean conditions. DC–DC switching converters and a battery fuel-gauge-based power management system were further developed to enable the system to operate in an energy-efficient manner. The technical functionality and real-time performance of the system were experimentally validated in a large-scale commercial graphite mine, precisely demonstrating accurate, stable, and continuous sensing of gas concentrations and environmental parameters. Moreover, the results revealed that the system exhibits strong responsiveness, capturing real-time variations in gas levels that correlate closely with the mine ventilation cycles. Accordingly, the developed system provides a scalable and cost-effective alternative to traditional monitoring methods, facilitating a transition from reactive safety measures to proactive and predictive risk management in underground mining environments.