Transition metal-catalyzed C-H alkylation has appeared as a well-built tool for the step-economical transformations of inert C-H bonds. Keeping in view the growing importance of these reactions, an outline of the application of transition metal catalysis in C-H functionalization/late-stage diversification processes has been demonstrated. In this review, we have focused on metals such as palladium, gold, scandium, silver, rhenium and manganese playing role as catalysts in C-H alkylation. Various alkylating agents, e.g., alcohols, alkyl halides, alkenes, diazo compounds and boronic acids, etc., have been used to get the products in good yields.