Nanomaterial-reinforced particle gel systems have attracted significant attention in the oil and gas industry for managing undesirable water production in mature oil fields. However, controlling excessive water production in challenging reservoirs, such as high-salinity, high-temperature reservoirs, remains a formidable task for the petroleum industry. This research paper provides a detailed account of the fabrication, chemical characterization, and performance assessment of a novel alumina nanomaterial reinforced particle gel (Al-RPG) designed for use in high-temperature reservoirs. The synthesis involved using alumina nanomaterial as a physical cross-linker or reinforcing agent, along with NaSS (styrene-4-sulfonic acid sodium salt) and DMA (N,N-dimethyl acrylamide) as monomers, NMBA (N,N-methylene bis (acrylamide)) as a chemical cross-linker, and 2,2-azobis(2-methylpropionamidine) dihydrochloride as an initiator. Chemical characterizations, including FT-IR, P-XRD FESEM, EDX, TGA (Thermal Gravimetric Analysis), DTG (Differential Thermogravimetric Analysis), and DSC (Differential Scanning Calorimetry), confirm the effective reinforcement of alumina nanomaterial in the polymeric matrix of Al-RPG. The developed Al-RPG can swell up to 18.74 times its dry weight in a 30000 ppm NaCl saline solution at room temperature conditions. A thorough assessment of the swelling characteristics has been performed, taking into account diverse factors including salinity, pH, temperature, composition of nanomaterials, and the presence of both monovalent and multivalent ions. Furthermore, a long-term thermal stability test of Al-RPG (0.30 wt % alumina nanomaterial reinforced particle gel) demonstrates excellent thermal resistance for 300 days at 150 degrees C in a 30000 ppm NaCl brine. Rheological studies indicate that Al-RPG possesses higher mechanical strength/toughness compared to a particle gel without reinforcement. Additionally, a sandpack flooding experiment assesses the water shutoff performance of the optimized Al-RPGs (0.30 wt % alumina-reinforced particle gel). The test data reveal that the plugging capacity (& Oslash;) of Al-RPG is 89.45, 88.32, 90.79, and 90.73 and the residual resistance factor (RRF) is 9.48, 8.56, 10.86, and 10.79, respectively. These results authenticate that the novel Al-RPG may be implemented for water control/shutoff treatment applications in the high-temperature reservoirs of mature oil fields.