Composite materials are created by combining two or more different materials, such as a filler or fibrous reinforcement dispersed in a polymer matrix. The primary goal of developing composites is to improve properties while reducing weight, making them ideal for the sustainable development of the automotive industry. Poly(lactic acid) (PLA) has emerged as a promising polymer matrix for composites due to its ecological and biodegradable nature, as well as its good mechanical properties (tensile strength and modulus of elasticity), though it remains limited when compared to engineering polymers such as acrylonitrile butadiene styrene (ABS) and acrylonitrile styrene acrylate (ASA). Cotton fibers have gained visibility in recent years as reinforcement in various matrices due to their low cost, renewable origin, and relative abundance. Incorporating cotton fibers into PLA can improve its mechanical properties, enhancing attributes such as tensile strength and stiffness, which makes the composite more suitable for applications requiring greater structural integrity. This article aims to study how to achieve a uniform distribution and strong chemical interaction between the PLA matrix and cotton fibers, that being crucial for the optimal composite performance required for the automotive industry. This study employed PRISMA protocol to conduct a systematic review of articles retrieved from four databases: ScienceDirect, Web of Science, Scopus and Engineering Village. The search query combined the following keywords: “PLA” AND “composite” AND “cotton”. The analysis of the research articles suggests that twin-screw extrusion is the preferred method for post-dispersion mixing due to its ability to control the process and optimization capabilities, resulting in homogeneous composite materials. Pre-dispersion techniques, including masterbatch, hydraulic presses or rheometers, produce concentrated mixtures of additive and polymer, effectively reducing fiber agglomeration during subsequent mixing. The use of solvent casting becomes an unfavorable option on an industrial scale due to the time required for production. However, it is still necessary for the validation and characterization of the material in laboratory scale, so that, in the future, an optimal formulation can be scaled up industrially with more robust machinery.