Photocatalytic coatings are considered sustainable materials as they only need sunlight for their activation and regeneration. Some photocatalytic disinfecting coatings are already commercialized, but many more are still in the developmental stage. Efficient and reliable analytical methodologies for testing the antimicrobial effects of photocatalytic coatings should therefore be used and further developed (1) to avoid inactive or unstable final products, (2) to allow fast, reproducible, and inexpensive antimicrobial activity measurements, and (3) to reflect real environmental conditions and challenges for these materials. Aiming to improve the existing methodologies of antimicrobial testing, this mini review summarizes and discusses the testing parameters and procedures in this expanding research field, including research on antimicrobial activity of photocatalytic coatings for different applications, i.e., self-cleaning/disinfecting coatings (films) and photocatalytic coatings for water and air treatment/disinfection.