The use of waste glass as fine aggregate in concrete offers a sustainable solution for reducing the environmental burden associated with glass disposal. However, incorporating waste glass as fine aggregate poses risks of expansion and strength reduction caused by alkali-silica reaction and the weak glass-paste interface. To address these challenges, the addition of mineral additives has shown promise in improving durability and offsetting strength reduction. Therefore, this paper presents findings on the sustainable use of waste glass in Portland cement concrete containing metakaolin. The waste glass replaced 10–40% of the fine aggregate, while metakaolin replaced 25% of the Portland cement. The addition of metakaolin in waste-glass-aggregate concrete significantly enhanced both strength and durability. All mixes containing waste glass and metakaolin exhibited higher 28-day compressive strength and better durability performance compared to the control. Among these, the 20% waste glass replacement achieved the highest compressive strength while the mixture containing 40% waste glass displayed outstanding resistance against oxygen permeation, water absorption, and chloride conduction. These findings demonstrate that waste glass can replace up to 40% of fine aggregate without compromising strength and durability when combined with metakaolin. This approach not only offers a sustainable means for concrete production but also addresses the environmental concerns associated with waste glass disposal.