Photocatalysis has attracted more and more attention as a possible solution to environmental, water, and energy crises. Although some photocatalytic materials have already proven to perform well, there are still some problems that should be solved for the broad commercialization of photocatalysis-based technologies. Among them, cheap and easy recycling, as well as stability issues, should be addressed. Accordingly, the application of gels, either as a photocatalytic material or as its support, might be a good solution. In this review, various propositions of gel-based photocatalysts have been presented and discussed. Moreover, an easy nanoarchitecture design of gel-based structures enables fundamental studies, e.g., on mechanism clarifications. It might be concluded that gels with their unique properties, i.e., low density, high specific surface area, great porosity, and low-cost preparation, are highly prospective for solar-energy-based reactions, water treatment, photodynamic cancer therapies, and fundamental research.