The all-inorganic lead-free perovskite Cs2SnI6 has gained considerable research attention due to its outstanding characteristics, including non-toxicity, robust stability, and superior photoelectric performance. In this research, we employed a simple yet robust chemical vapor deposition technique to successfully grow ultra-thin 2D Cs2SnI6 flakes on a mica substrate, achieving a minimal thickness of just 8 nm and a significant lateral size of up to 48 μm. The obtained 2D Cs2SnI6 flakes displayed an extended photoluminescent lifetime of approximately 1.44 ns and exceptional stability, maintaining their crystal structure intact over a period of 60 days. The photodetectors fabricated from Cs2SnI6 flakes demonstrated a broad ultraviolet to near-infrared response range (365–1342 nm), with a responsivity of up to 6.25 × 105 A W−1. They additionally displayed rapid rise and decay times of 31.32 ms and 72.42 ms, respectively, with an external quantum efficiency reaching as high as 1.92 × 106 %, and a detectivity achieving 1.27 × 1011 Jones. This research serves as a critical step forward in enabling the facile yet robust synthesis of stable, all-inorganic ultra-thin lead-free perovskites, paving the way for innovation in environmentally friendly optoelectronic devices.