ABSTRACTJanus hairy nanoparticles (JHNPs) represent a new class of hybrid materials with a nanoparticle core and a layer of bicompartmentalized polymer brushes. This unique structure combines the complex properties of polymer brushes, the amphiphilic nature of surfactant, and the mechanical, optical, and electronic properties of nanoparticles. Over the past decade, tremendous efforts have been devoted to synthesizing JHNPs and understanding their structure and properties. In this review, we will summarize the recent progresses in the field, including fabrication approaches and the self‐ and directed assembly behavior of such JHNPs. We will specifically focus on the newly developed polymer single crystal directed nanoparticle assembly approach. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1620–1640