This study investigates the influences of recycled waste glass powder (RGP) on the carbonation behaviour of sodium carbonate activated ground granulated blast furnace slag (GGBS) mortars. The effect of activator dosages, types and RGP addition on resistance to carbonation are evaluated. The results indicate a high dosage of sodium carbonate or water glass combination as activator always can enhance the ability of resistance to carbonation. Furthermore, the addition of 30% RGP in the GGBS binder system seems to significantly improve the resistance to carbonation of mortars. The carbonation shrinkage is reduced after RGP incorporation; at the same time, a higher strength performance is observed. The RGP in sodium carbonate activated GGBS blends shows no influence on the species of reaction products. However, after carbonation, the sample containing RGP promotes the formation of nahcolite, while less bound water loss and calcium carbonate formation are identified. A high volume of gel pores (<10 nm) is formed in the RGP sample compared to specimens only containing GGBS. These properties contribute to a better resistance to carbonation for RGP containing sodium carbonate activated GGBS mortars.