Put a label on it: Carbondioxide with H2 is shown to be an efficient and selectivemethylation reagent for aromatic and aliphatic amines (see scheme; acac=acetylacetonate, triphos = 1,1,1‐tris(diphenylphosphanylmethyl)ethane). A variety of functionalized amines including 13C‐labelled drugs were obtained with good yields and functional‐group tolerance.