Polyphosphoesters have a high impact in bio-related fields because of their biocompatibility and structural similarities to naturally occurring molecules. The phosphoester backbone is degradable through spontaneous hydrolysis and the degradation is accelerated with enzymatic treatment. Furthermore, a variety of polyphosphoesters can be obtained by ring-opening polymerization because cyclic phosphoranes as monomers are synthesized from the condensation of alcohol and chloro-cyclic phosphorane. Here, a modern synthetic route of polyphosphoesters with the use of organocatalysts is introduced. For this synthetic route, the molecular weight of polyphosphoesters could be controlled and the kinetics coincided with the theoretical value. In addition, higher molecular weight polymers with good yield and narrow distribution could be obtained. Polyphosphoesters formed in a ring-opening polymerization can have essentially desired topology through appropriate selection of the functional initiator. They can be used as building blocks in constructing self-assembly. The intracellular delivery of drugs and nucleic acids incorporated with polyphosphoester associates is also mentioned in this review.