Abstract Genetic testing plays an important role in human health management and disease prevention. However, traditional genetic testing methods have been unable to fulfill the current diagnostic needs owing to several limitations, including high cost, complexity, and difficulty in performing. Smartphones have multiple inherent advantages, such as easy portability, ubiquity, fast processing speed, and excellent imaging capabilities, and have enormous potential in realizing rapid on‐site genetic testing. The present review documents the research progress of smartphone‐based optical imaging biosensors in the fields of colorimetry, fluorescence, and microscopic imaging for genetic testing. Furthermore, the review describes their potential applications in diagnostics, which range from infectious diseases to hereditary diseases and cancers. Finally, the challenges and perspectives of smartphone‐based optical imaging biosensors regarding genetic testing are discussed.