With generations of efforts to understand RNA functions in diverse cellular processes, RNA ‐binding proteins ( RBPs ) have emerged to be one of the central players in regulating RNA ‐related pathways. RBPs control almost all aspects of RNA processing via recognizing their RNA target(s). Most of these proteins have a modular configuration, with one or more RNA ‐binding domain for target recognition and various functional modules to affect the metabolism and biological functions of RNA . Thus, engineering RNA ‐binding factors with customized specificity and function is extremely useful in biological and medical research. In this review, we discuss the current advances in engineering RBPs that specifically bind to diverse targets, with emphasis on the design strategies and their applications as new biological tools in various aspects of RNA metabolism and function. WIREs RNA 2015, 6:597–613. doi: 10.1002/wrna.1296 This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein–RNA Recognition RNA Interactions with Proteins and Other Molecules > Protein–RNA Interactions: Functional Implications