A poor or mediocre stereoselectivity is a key roadblock for a chiral catalyst to find practical adoptions. We report a facile method to create a tunable chiral space near a chiral catalyst to augment its selectivity. The space was created rationally through templated polymerization within cross-linked micelles, using readily available amino acid derivatives. It provided gated entrance of reactants to the catalyst, enabling a mediocre prolinamide to catalyze aldol condensation in water with excellent yields and ee, in a size- and shape-selective manner.