Resin-based pit fissure sealants (RBS) are used to prevent occlusal caries in children. The success of RBS in preventing dental caries is largely influenced by its retention on the tooth surface, which is also affected by its physicomechanical properties. The physicomechanical properties of RBS can be enhanced through the addition of fillers. With the advent of nanofillers, the physicomechanical properties were improved without altering RBS flowability. The present study developed an RBS with a 70 wt% resin matrix and 30 wt% nanofillers. The resin matrix consisted of urethane dimethacrylate (55 wt%), triethylene glycol dimethacrylate (45 wt%), camphoroquinone (0.3 wt%), and 2-(dimethylamino) ethyl methacrylate (0.7 wt%). Silane-treated rice husk-derived nanosilica (20 wt%) and nanohydroxyapatite (10 wt%) were added as fillers. Clinpro, Fissurit FX, and an unfilled sealant were controls. All RBS were tested for surface roughness, Vickers hardness, flexural strength, and flowability. Statistical analysis with oneway ANOVA revealed significant differences between groups in surface roughness, hardness, flowability (p < 0.001), flexural strength, and flexural modulus (p < 0.05). Experimental sealants had higher flexural strength (78 MPa) and flow distance (29.05+1.16 mm) than commercial controls.However, the surface roughness of experimental sealants (0.25+0.08 μm) was higher than Clinpro (0.087+0.027 μm) but lesser than Fissurit FX (0.35+0.19 μm). The Vickers hardness of experimental sealants (23+1.63 VHN) was less than Fissurit FX (28.80+1.69 VHN) but higher than Clinpro (21.74+1.68 VHN). This novel RBS had physicomechanical properties comparable to commercial sealants. The use of nanosilica from rice husk makes this pit and fissure sealer sustainable and environmentally friendly in dentistry.