Hypervalent iodine chemistry is now a well-established area of organic chemistry. Novel hypervalent iodine reagents have been introduced in many different transformations owing to their mild reaction conditions and environmentally friendly nature. Recently, these reagents have received particular attention because of their applications in catalysis. Numerous hypervalent iodine-catalyzed oxidative functionalizations such as oxidations of various alcohols and phenols, α-functionalizations of carbonyl compounds, cyclizations, and rearrangements have been developed successfully. In these catalytic reactions stoichiometric oxidants such as mCPBA or oxone play a crucial role to generate the iodine(III) or iodine(V) species in situ. In this Focus Review, recent developments of hypervalent iodine-catalyzed reactions are described including some asymmetric variants. Catalytic reactions using recyclable hypervalent iodine catalysts are also covered. Hypervalent iodine reagents have a wide range of reactivities and can be used under mild reaction conditions. Their applications in catalysis have led to a number of oxidative transformations that are summarized here. Hypervalent iodine catalysts generated in situ by oxidation of iodoarenes with stoichiometric oxidants such as m-chloroperbenzoic acid or oxone allow metal-free and environmentally friendly reactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.