The Suzhou granitic pluton is the first identified Nb–Ta-rich granite in China. Elucidating its magmatic-hydrothermal evolutionary process is critical for advancing our understanding of petrogenetic processes and Nb-Ta mineralization mechanisms in the region. This study for the first time systematically conducts petrographic, geochemical and chronological studies on titanite in the amphibole- and biotite-bearing granite within the Suzhou pluton. Based on the mineralogical and geochemical characteristics of titanite, the magmatic-hydrothermal evolution sequence and its constraints on Nb-Ta mineralization are clarified. The titanite in Suzhou granite records both magmatic and hydrothermal evolution: (a) Magmatic titanite exhibits relatively homogeneous compositional zoning, with high LREE (mean: 16,355 ppm) and HFSE contents (e.g., Nb averaging 5,550 ppm), elevated high TiO? content, Th/U ratios, crystallization temperatures (680 ± 30°C), as well as lower CaO content and Lu/Hf ratios. (b) Hydrothermal titanite is primarily divided into two stages. Early-stage hydrothermal titanite formed in a high-fO? hydrothermal environment, characterized by low LREE (mean: 661 ppm) and HFSE contents (e.g., Nb averaging 880 ppm). In contrast, late-stage secondary hydrothermal titanite crystallized in a relatively reduced hydrothermal fluids, with geochemical features showing significantly enriched Nb content, reaching up to 8,796 ppm. LA-ICP-MS dating yielded U–Pb ages of 125.2 ± 7.2 Ma for magmatic titanite and 125.4 ± 2.8 Ma for hydrothermal titanite, indicating their collective formation within the Early Cretaceous granitic magmatic-hydrothermal system. During hydrothermal fluid evolution, the interaction of F-rich fluids with titanite, amphibole, and biotite triggered non-equilibrium dissolution, releasing substantial HFSEs (e.g., Nb, Ta) and REEs into hydrothermal fluid. These elements were subsequently remobilized by F-enriched, relatively reduced hydrothermal fluids, either precipitated as secondary hydrothermal titanite (depleted in LREE with exceptionally high Nb concentrations up to 8,796 ppm) and ilmenite around primary minerals, or migrated over short distances to form Nb-Ta-enriched minerals such as fergusonite-(Y) and samarskite-(Y). In short, titanite exhibits progressive depletion in REE and HFSE (e.g., Nb, Ta) as the granitic system evolves from magmatic to hydrothermal regimes, and F-driven metasomatism (e.g., biotite alteration) promotes Nb enrichment. This indicates that the compositional evolution (major and trace elements) and microtextural features of titanite effectively archive both magmatic and subsequent hydrothermal processes. Consequently, titanite emerges as a new indicator for tracing Nb-Ta mineralization in granitic systems.