Integrating phase change materials (PCMs) into textiles is primarily driven by their exceptional thermo-regulating properties, which arise from their ability to absorb, store, and release thermal energy during phase transitions. This unique capability makes PCMs highly effective in maintaining temperature stability and enhancing the comfort of textile products. This chapter provides a comprehensive review of PCMs and their role in thermal regulation within textiles. It begins with an overview of PCMs, including their classification and the mechanisms underlying their phase change behavior. It further discusses the process of microencapsulation, a key technique used to enhance the stability and performance of PCMs, along with various fabrication methods for integrating PCMs into textile materials. In addition to addressing the technical aspects, the chapter examines characterization techniques used to evaluate the performance of PCM-incorporated textiles and highlights their diverse applications across industries, such as apparel, bedding, and technical textiles. It also outlines the criteria for selecting suitable PCMs based on specific requirements, including thermal properties, durability, and compatibility with textile substrates, while providing a detailed cost analysis in light of current market trends and demands. The chapter concludes by addressing the environmental impacts and challenges of using PCMs, such as sustainability concerns and lifecycle considerations.