Recently, organ-on-chips have become a fast-growing research field with the widespread development of microfluidic chips and synthetic materials in tissue engineering. Due to the existing cardiotoxicity of many cardiovascular drugs, heart-on-chips which are promising to replace traditional animal models have been extensively researched and developed to mimic human organ functions in vitro. The heart-on-chips mainly focus on cardiac mechanics, which is regarded as the central indicator of in vitro heart models and drug testing. Traditional methods for the detection of myocardial mechanics have been demonstrated complex and inefficient in heart-on-chips. Therefore, photonic crystal materials with unique optical properties have attracted interests and have been introduced into the heart-on-chips, developing a visualized self-reporting system for cardiomyocytes activity monitoring. In this review, photonic crystal-based heart-on-chips for biosensing are introduced, as well as the fabrication methods and design criteria of them. The characterizations of the photonic crystal materials are classified into optical properties and structural properties, and their applications in cell culture and biosensing are further discussed. Then, several representative examples and developments of the integration of photonic crystal materials into microfluidic chips are described in detail. Finally, potentials and limitations are put forward to promote the development of the photonic crystal-based intelligent heart-on-chips.