The architecture, composition and molecular weight (MW) of polymers and copolymers made via free radical polymerization are important parameters that affect the end-use of both these polymeric materials and the nanoparticles that they compose. In order to gain control over these parameters, several controlled radical polymerizations (CRPs)—such as atom transfer radical polymerization (ATRP) and reversible addition fragmentation chain transfer (RAFT) polymerization—have been developed over the past few decades. However, the toxicity, biocompatibility and degradation profile of these materials are emerging as key features for their final disposal and for certain applications, such as the synthesis of biomaterials. In this case, polyesters made via ring opening polymerization (ROP) are preferred due to the control over the synthesis that this technique allows as well as the biodegradability of the final material. The combination of ROP with CRP techniques has allowed for the synthesis of polymeric surfactants capable of self-assembling into biodegradable nanoparticles (NPs) for biomedical applications. This review presents and critically discusses the primary strategies for the synthesis of highly engineered colloids via the combination of ROP with two CRP techniques: ATRP and RAFT polymerization.