Covalent triazine frameworks (CTFs) have attracted a great deal of attention as an attractive new class of visible light-active, metal-free, and polymer-based heterogeneous photocatalysts. CTFs have demonstrated promising characteristics such as synthetic diversity, stability, nontoxicity, pure organic nature, and enhanced ordered structure. In this review, we aim to summarize the recent developments in CTFs ranging from novel preparation methods to critical factors that directly impact their photocatalytic efficiency. Various physical and chemical design strategies for morphology, band structure, charge separation, and transfer optimization described in the literature are discussed. Emphasis is placed on the enhancement and maximization of photocatalytic efficiencies of specific applications such as photoredox organosynthesis, water splitting, CO2 photoreduction, H2O2 generation, etc.