AbstractThis article presents a catalytic approach for site‐selective α‐C−H functionalization of N‐benzyl tetrahydroisoquinolines, which are important tertiary amine derivatives. Using iron salt as a catalyst, we have selectively functionalized carbon‐hydrogen bonds of tertiary amine molecules with diverse moieties, such as imidazopyridine, indoles, and phenylacetylenes. The method offers a broad substrate scope and excellent functional group tolerance, making it a valuable tool for the synthesis of complex molecules. A mechanism is also proposed based on control experiments, which explains the probable reason for selectivity. This iron‐catalyzed C−H functionalization represents a significant advancement in the field of organic synthesis, showcasing the potential of iron catalysis for the construction of valuable chemical motifs.