Biomimetics has provided solutions to many of the intricate problems of humans since time immemorial. Photocatalysis is one such application that draws inspiration from photosynthesis, the life-giving chemical reaction. Given the sedentary life choices of humans nowadays, and indoor environments being the source of a wide range of air pollutants, photocatalysis is the trending science defining the air purification process. Existing means of air purification, namely, absorption, adsorption, condensation, ionization, and filtration, have their own constraints. Photocatalytic oxidation-based air purifiers and building materials, and photocatalysis usage in heating, ventilating, and air conditioning are the emerging saviors of human health in the indoor environment. Photosensitive semiconductors absorb UV light to form reactive OH radicals in the presence of oxygen and water vapor. Generated free radicals are then involved in a series of reactions with indoor air pollutants, to mineralize them into CO2 and water. Photocatalytic compounds are also utilized to construct concrete with air-purifying coating by integrating photocatalyst particles within a thin concrete surface layer. Such integration of photocatalysts into building materials is a good technological application for urban air pollution mitigation. After the COVID-19 pandemic, the application of photocatalytic oxidation-based air purifiers has increased even more, and extensive research is being done to improve their efficiency and reliability. For outdoor air pollution, PCO is a green technology as sunlight is a natural source that provides photonic energy as a driving force to initiate the chemical reactions. Such technological usage opens the scope of sustained solutions for air pollution in indoor and outdoor environments yet requires continuous research for enhancing the efficiency.