AbstractA single‐atom Pt₁/CeO₂ catalyst formed by atom trapping (AT, 800 °C in air) shows excellent thermal stability but is inactive for CO oxidation at low temperatures owing to over‐stabilization of Pt²⁺ in a highly symmetric square‐planar Pt₁O₄ coordination environment. Reductive activation to form Pt nanoparticles (NPs) results in enhanced activity; however, the NPs are easily oxidized, leading to drastic activity loss. Herein we show that tailoring the local environment of isolated Pt²⁺ by thermal‐shock (TS) synthesis leads to a highly active and thermally stable Pt₁/CeO₂ catalyst. Ultrafast shockwaves (>1200 °C) in an inert atmosphere induced surface reconstruction of CeO₂ to generate Pt single atoms in an asymmetric Pt₁O₄ configuration. Owing to this unique coordination, Pt₁^δ+ in a partially reduced state dynamically evolves during CO oxidation, resulting in exceptional low‐temperature performance. CO oxidation reactivity on the Pt₁/CeO₂_TS catalyst was retained under oxidizing conditions.