ortho-C-alkylation of unprotected anilines with a variety of styrenes and alkenes using a univalent cationic indium(I) catalyst is reported. Mechanistic studies revealed that the reaction likely proceeds via a tandem hydroamination/Hofmann–Martius rearrangement. The high compatibility between the cationic indium(I) complex and primary anilines led us to develop an In(I)+-catalyzed hydroamination of alkenes