The application of thermal spray (TS) coatings on polymers and polymer matrix composite substrates has recently attracted considerable scholarly interest, leading to the publication of numerous review articles that articulate the current advancements in the field. Nonetheless, most of these reviews have primarily concentrated on metallization methodologies, including cold spray (CS) and thin-film deposition techniques. Despite the widespread implementation of CS and metallic coatings, alternative TS methodologies, such as arc, plasma, and combustion-based spraying, along with various coating materials like ceramics, polymers, and composites, are similarly gaining prominence. This review offers a comprehensive analysis of various feedstock materials and TS techniques, with a particular focus on their compatibility with polymer-based substrates. The aim is to accomplish a wide array of augmented material characteristics while accentuating the unique attributes of each TS technique. Detailed discussion is provided on each TS process, including particle–substrate interactions, required preparation, interlayers, coating buildup, and bonding mechanisms. By synthesizing the available literature, this review presents a comprehensive overview of the historical development of TS technologies, outlining major innovative advancements. It seeks to elucidate researchers' contributions to addressing deposition mechanism challenges and to underscore the merits and limitations of each TS methodology. The coatings are analyzed in terms of the properties they impart to the substrate, with a focus on potential applications. Examples of practical applications in various fields, such as thermal protection, biomedical engineering, electrical engineering, and tribology, are presented. Furthermore, the review summarizes the challenges facing the development of these techniques as efficient treatments for P/PMC substrates provide guidelines for future research. Novel application domains are proposed based on the most recent research outcomes. Ultimately, this critique aspires to facilitate the selection of feedstock substances and spraying methodologies, taking into consideration the intended application.