The manipulation of the transition states of a chemical process is essential to achieve the desired selectivity. In particular, transition states of chemical reactions can be significantly modified in a confined environment. We report a catalytic reaction with remarkable amplification of stereochemical information in a confined water cage. Surprisingly, this amplification is significantly dependent on droplet size. This water-induced chirality amplification stems from the hydrophobic hydration effects, which ensures high proximity of the catalyst and substrates presumably at the transition state, leading to higher enantioselectivity. Flow and batch reactors were evaluated to confirm the generality of this water-induced chirality amplification. Our observation on efficient chiral induction in confined water cages might lead to an understanding of the chirality amplification in the prebiotic era, which is a key feature for the chemical evolution of homochirality.