<p>Modular Microfluidic Platforms (MMPs) have gained prominence in biological applications due to their modularity, ease of component replacement, scalability, and ability to conduct multiplexed experiments. However, the lack of standardized connection methods between microfluidic modules limits widespread adoption and reproducibility of MMPs. This review proposes a framework for categorizing MMPs by their assembly configurations and fabrication techniques, with a focus on connection methods organized according to geometric arrangements (e.g., in the x–y plane, along the z-axis, or in the x–y–z coordinate system) that define the spatial organization and integration of modules. Additionally, this review discusses key biological applications of MMPs, such as droplet generation, sample harvesting, biomarker detection, and microphysiological systems, and highlights how modularity enhances the adaptability and functionality of MMPs in these areas. Establishing clear criteria for MMPs categorization should help standardize MMPs design, improve reproducibility, and foster innovation in biological research.</p>