A huge prospect of lead halide perovskites can be found in the fields of optoelectronics and photocatalysis. However, the main obstacle to their photocatalytic application is their toxicity. To shake off these issues, lead-free Cs 3 Sb 2 I 9 perovskite microcrystals with different morphologies were synthesized via a simple hot-injection approach. Furthermore, the as-prepared Cs 3 Sb 2 I 9 microcrystals were utilized for photocatalytic CO 2 reduction, achieving a total electron yield of 14.2 μmol g –1 under visible-light irradiation (λ ≥ 420 nm, 300 W Xe lamp) within 3 h. Our work here provides an idea for the application of lead-free perovskites for photocatalytic CO 2 reduction.