The copper industry generates nearly 25 million tons of slag annually, which is stockpiled or landfilled, leading to land occupation and the potential for soil and water contamination alongside the environmental burden of the construction sector, which accounts for up to 9% of global CO2 emissions and massive raw material consumption. The need for low carbon, resource-efficient binders has spurred interest in geopolymerization, or the alkali activation of aluminosilicate residues, as a pathway to valorize industrial by-products. The objective of this review is to analyze, synthesize, and critically evaluate the scientific evidence on alkali-activated materials derived from Cu slag, emphasizing the synthesis pa rameters, mechanical and durability behavior, and environmental performance. The review applies the PRISMA 2020 methodology. The analysis of the 57 reports shows that copper slag—used alone or with metakaolin or blast furnace slag—can produce alkali-activated materials with high compressive strength, refined pore structures, and cradle-to-gate CO2 reductions of up to 80%. Cu slag is not a chemically homogeneous precursor, and its influence on performance depends on the activation strategy and dosage rather than the slag content alone. Overall, this review consolidates dispersed findings, identifies research gaps, and proposes a framework for sustainable valorization in the form of low-carbon construction materials.