The development of microfluidic technology has revolutionized fields such as biomedical diagnostics, chemical analysis, and environmental monitoring by enabling precise fluid control and integration of multiple functions within compact devices, enhancing accuracy, efficiency, and cost-effectiveness. In the field of microfluidics, the material of the device determines its functionalities. Among the various materials used in microfluidic chip fabrication, thermoplastics have emerged as a particularly promising and significant choice. Thermoplastic materials offer several advantages for microfluidic applications due to their inherent properties and processing benefits. These materials provide excellent optical transparency, which is crucial for optical detection methods. They also demonstrate excellent resistance to chemicals, maintain thermal stability, and are easy to fabricate, thereby supporting the swift prototyping and large-scale manufacturing of microfluidic devices. Additionally, thermoplastics can be processed using various techniques such as hot embossing, injection molding, and thermoforming, allowing for high precision and reproducibility in microchannel structures. This paper provides a comprehensive overview of current fabrication methods for microchannels in thermoplastic microfluidic devices and offers a comparative analysis of different fabrication strategies to guide researchers in selecting appropriate techniques.