Numerous reports have suggested that the performance of organic optoelectronic devices based on organic field-effect transistors (OFETs) is largely dependent on their interfaces. Self-assembled monolayers (SAMs) have been commonly used to engineer the interfaces of high-performance devices, particularly due to their well-defined structures and simple operation process through simple chemical adsorption growth. In this review, the structures of OFETs and SAM-modified OFETs are described, while different SAMs have been characterized. Furthermore, recent advances in the interface engineering of OFETs are described, the applicability of SAMs in functional devices of OFETs is reviewed, and existing problems and future developments in this field have been identified.