This review paper focuses on present issues concerning the use of polyaniline–TiO2 heterostructures as potentially efficient photocatalysts. Conducting polymers such as polyaniline (PANI) are used in the preparation of heterojunction systems with metal oxides like titania to overcome their inherent limitations, e.g., their sole absorption of UV light and overly fast recombination of charge carriers. This review discusses preparation methods, the properties of resultant products and mechanistic aspects. An important part of this paper is its presentation of the major challenges and future perspectives of such photocatalytic materials.