This study investigates the impact of leaching on the carbonation resistance of alkali-activated materials with varying calcium content. Six binder compositions were tested, combining ground blast furnace slag and calcined clay, with CaO content ranging from ~0% to ~40%. Samples underwent three conditions: no leaching, two weeks of leaching (2Le), and five leaching-carbonation cycles (5LCC). Carbonation tests were performed under natural conditions and 1% CO2 for reference and 2Le samples, while 5LCC samples were exposed solely to accelerated carbonation. Under natural carbonation, the typical relationship between carbonation resistance and the water/(CaO+MgOeq+Na2Oeq+K2Oeq) ratio was observed for both the reference and 2Le samples, with an increase in carbonation rate in compositions containing more than 40% calcined clay. In accelerated carbonation conditions, 2Le and 5LCC conditions showed slightly improved carbonation resistance compared to the reference samples, except for the mixtures containing only calcined clay (C100) and the mix with 40% calcined clay (C40S60). The poor performance of C100 was attributed to its low reactivity after 28 days, which resulted in significant sodium leaching and reduced activation of the calcined clay. Although C40S60 outperformed non-leached samples, its carbonation resistance slightly decreased in leached and accelerated carbonation samples due to reduced gel phase formation; however, this reduction was significantly less than that of C100. These findings suggest that while leaching can enhance carbonation resistance by reducing excess alkalis, low-reactivity systems, e.g. based solely on calcined clay, are more susceptible to degradation.