Functional organic field‐effect transistors (OFETs) have attracted increasing attention in the past few years due to their wide variety of potential applications. Research on functional OFETs underpins future advances in organic electronics. In this review, different types of functional OFETs including organic phototransistors, organic memory FETs, organic light emitting FETs, sensors based on OFETs and other functional OFETs are introduced. In order to provide a comprehensive overview of this field, the history, current status of research, main challenges and prospects for functional OFETs are all discussed Functional organic field‐effect transistors (OFETs) have attracted increasing attention due to their abilities in photoswitching, light detection, light emission, signal storage, sensing, and other areas and have many potential commercial applications. This review focuses on functional OFETs including organic phototransistors, organic non‐volatile memory FETs, organic light emitting FETs, sensors based on OFETs and other functional OFETs.