The construction industry generates vast quantities of non-biodegradable waste, such as glass cullet and plastic scraps, posing serious environmental challenges that require innovative recycling strategies in concrete production. This study evaluates the mechanical and physical properties of high-performance concrete incorporating glass powder (GP) and ultra-fine glass powder (UFGP) as partial replacements for fine aggregate, together with low-density polyethylene (LDPE) granules as a partial substitute for coarse aggregate, using locally available quartz-based materials. Ten distinct concrete mix designs were prepared using Ordinary Portland Cement (OPC) Grade 53, fractionated quartz sand, and crushed vein quartz as coarse aggregate. GP and UFGP replacement levels ranged from 0% to 20%, while LDPE replacement levels varied from 0% to 15%. All specimens were cured for 28 days and subsequently tested for compressive strength, water absorption, ultrasonic pulse velocity (UPV), modulus of elasticity, and density. The results showed that the mix containing 10% GP and UFGP replacement (Mix B) achieved the highest compressive strength of 61.98 MPa, representing a 10.9% improvement over the control mix, which recorded 55.91 MPa. The hybrid mix (Mix E), incorporating 10% GP and UFGP together with 5% LDPE, attained a compressive strength of 57.38 MPa while reducing the specimen weight to 2425.95 g and achieving the lowest water absorption rate of 0.54%. However, increasing the LDPE content beyond 10% resulted in significant strength deterioration; for example, Mix K, containing 15% LDPE, recorded a compressive strength of only 29.16 MPa. The incorporation of GP and UFGP improved workability, as indicated by slump values increasing from 45 mm to 210 mm. Conversely, the addition of LDPE gradually reduced the modulus of elasticity from 37 GPa to 25 GPa. Ultrasonic pulse velocity measurements of 5.51 km/s for Mix B confirmed that GP and UFGP enhanced concrete density and internal compactness, whereas the inclusion of LDPE adversely affected internal homogeneity. These findings suggest that optimal combinations of GP, UFGP, and low percentages of LDPE can produce sustainable lightweight concrete suitable for structural applications, effectively diverting waste materials from landfills while maintaining acceptable mechanical performance and durability.