Swift global transition toward sustainable food systems led to increasing demand for alternative protein sources capable of replicating the nutrition and sensory attributes of animal meat. Plant-based meat analogues (PBMA) are central to this shift, driven by consumer interest in environmental management, health, and ethical considerations. This review examines the comparative functionality and processing behavior of major plant proteins; soy, pea, and wheat, and a diverse range of emerging sources such as faba bean, lentil, chickpea, and mung bean. Particular emphasis is placed on their structural composition, amino acid balance, and key functional properties including gelation, emulsification, and water- and oil-holding capacities that govern texture, juiciness, and mouthfeel. High-moisture extrusion (HME), the dominant technology for PBMA production, is discussed with a focus on how heat, shear, and moisture induce protein unfolding, alignment, and cross-linking to create fibrous, meat-like structures while influencing digestibility and amino acid availability. Protein blending strategies are highlighted as tools to improve texture, nutritional quality, and processing performance while reducing dependence on allergenic or monoculture-prone crops. Ingredient innovations such as hydrocolloids, modified starches, and tannin-mediated protein modification are reviewed for their roles in enhancing structural integrity, moisture retention, and flavor, and for mitigating anti-nutritional factors. The article presents a comprehensive framework for optimizing PBMA by integrating insights from food chemistry, processing, engineering, and sustainability science. The synthesis of ingredient functionality, extrusion dynamics, and sensory outcomes offers a pathway toward the development of next-generation meat analogues that are nutritionally balanced, environmentally responsible, and broadly acceptable to consumers.