Microfluidics is known to be an enabling technology in a wide range of fields, particularly the chemical and biological sensing fields. Together with the development of technology, the integration of optics into microfluidic devices has enabled new directions of research and applications. As an example, owing to unique advantages in flow manipulation and sensitive signal detection, various optofluidic platforms have been developed to detect a wide range of disease-related biomarkers. Similarly, microfluidic devices integrated with portable imaging systems are increasingly being reported for various biomedical diagnostic applications. Through this Special Issue, we aim to highlight the development of optics-integrated microfluidic platforms and their diagnostic applications. Original research papers and review articles on the topics described above are welcome.