Coal gangue is a prominent solid mine waste with significant environmental concerns due to its composition, threatening human health and ecosystems due to its massive disposition. Despite this, a high content of aluminosilicate in coal gangue makes it as a resource of developing cementitious properties which in turn reduce cement consumption. Activation of coal gangue involves improving the reactivity of coal gangue in terms of stimulating the aluminosilicates present within. This study investigates the physical, chemical, and mineralogical characteristics of coal gangue from diverse locations and interprets various activation methods to enhance the reactivity for geopolymerization. This review provides comprehensive insights into the methods of activation of coal gangue for geopolymerization and identifies the most effective method of activation. The findings emphasize the emerging importance of composite activation as a viable strategy for converting coal gangue into a valuable resource while addressing environmental challenges. The combined use of physical and chemical activation methods enhances the structural integrity of the geopolymer and improves its physical properties. Besides this, geopolymer synthesized from activated coal gangue demonstrates enhanced adsorption capabilities for heavy metal ions which contributes to environmental remediation efforts.