This chapter summarizes recent investigations into the mechanical behavior of matrix-free hairy nanoparticles using molecular simulation techniques. Generic as well as systematic coarse-graining techniques are presented, highlighting emerging methods for chemistry-specific modeling of polymeric materials. Applications of coarse-graining to study assembled hairy nanoparticle systems are overviewed, with an emphasis on quantitative structure–property relationships obtained from these investigations. Comparisons of simulations with theoretical scaling relationships such as the Daoud-Cotton theory and experimental data are provided. Methods to accelerate the design space through upscaling techniques and metamodel development are briefly overviewed. Key physical insights obtained from these studies on the effects of grafting density, grafting length, and polymer chain chemistry are mentioned throughout the chapter to illustrate the importance of modeling contributions. A brief outlook into the prospects of using novel mesoscopic approaches such as those based on potentials of mean force is noted. The chapter concludes with a summary and outlook on the state of the art of the computational design of assembled hairy nanoparticles.