Rhodium(III)-catalyzed atroposelective C–H selenylation of 1-aryl isoquinolines has been achieved. The direct C–H selenylation reaction between 1-aryl isoquinolines and 2-(phenylselanyl)isoindoline-1,3-dione in the presence of the chiral SCpRh(III) complex afforded a series of axially chiral 1-aryl isoquinoline selenides in up to 95% yield and 96% ee. The reaction features mild conditions and a broad substrate scope. DFT calculations revealed that the C–Se bond formation step proceeds through a formal SN2 pathway.