Chiral 1,2-aminoalcohols are privileged motifs in bioactive molecules, yet their stereocontrolled synthesis remains a challenge. Here, we report a general, metal-free photoredox Minisci strategy that converts bicyclic N,O-acetals derived from β-hydroxy-α-amino acids into enantiopure 2-hetaryl-1,2-aminoalcohols with complete stereoretention. This diastereoselective radical α-hetarylation proceeds under visible light and mild conditions, tolerating diverse substitution patterns on both the heteroarene and the bicyclic scaffold. Combined experimental and quantum mechanical studies reveal that dispersion (CH/π) interactions between the incoming heteroarene and the bridgehead methyl group govern the unexpected facial selectivity in the C-C bond-forming step. The products serve as versatile precursors to medicinally relevant scaffolds, and the scalability of the process highlights its synthetic utility. This work establishes a broadly applicable platform for the stereocontrolled radical functionalization of amino acid derivatives.