A concise approach for the synthesis of structurally diverse indoles enabled by Rh^III-catalyzed switchable C2 C–H olefination and alkylation of N-quinolinyl indoles with alkenes as well as highly efficient C–H deuteration is described. The reaction can be conducted under practical reaction conditions, with a broad substrate scope and good tolerance of various functional groups. The potential value of this synthetic methodology is shown by the diverse late-stage modification of the products, thereby providing a straightforward route to access functionalized indoles, especially indole-based P,N ligands.