Well defined hydrophilic or amphiphilic polymer latexes and polymer composites in submicron size have important applications in various fields such as drug delivery, industrial catalysis, and coatings. However, these well defined polymer latexes and composites are usually difficult to produce in large scale due to the issue of mixing and heat transfer. To overcome the above problems, RAFT inverse miniemulsion polymerization is applied here as a unique approach to synthesize these nanosized hydrophilic polymer latexes and composites. Moreover, the polymers derived from RAFT inverse miniemulsion polymerizations maintain their “livingness” and can be easily functionalized. The kinetic behavior of inverse RAFT miniemulsion polymerization is studied and effects of reaction parameters on inverse miniemulsion polymerizations are investigated. Responsive nanoparticles are synthesized and the applications of RAFT inverse miniemulsion polymerization are also discussed.