Abstract Platinum telluride (PtTe2), a member of metallic transition metal dichalcogenides, provides a new platform for investigating various properties such as type‐II Dirac fermions, topological superconductivity, and wide‐band photodetection. However, the study of PtTe2 is largely limited to exfoliated flakes, and its direct synthesis remains challenging. Herein, we report the controllable synthesis of highly crystalline 2D PtTe2 crystals with tunable morphology and thickness via chemical vapor deposition (CVD) growth on Au substrate. By adjusting Te amount and substrate temperature, anisotropic and isotropic growth modes of PtTe2 were realized on the solid and molten Au substrates, respectively. The domain size of PtTe2 crystal was achieved up to 30 μm, and its thickness can be tuned from 5.6 to 50 nm via controlling the growth time. Furthermore, a metal–PtTe2–metal structural device was fabricated to validate the wide‐band terahertz (THz) photodetection from 0.04 to 0.3 THz at room temperature. Owing to the high crystallinity of PtTe2 crystal, the photodetector acquires high responsivity (30–250 mA W‐1 from 0.12 to 0.3 THz), fast response rate (rise time: 7 μs, decay time: 8 μs), and high‐quality imaging ability. Our work demonstrates the feasibility for realistic exploitation of high‐performing photodetection system at THz band based on the CVD‐grown 2D Dirac semimetal materials.