Recent developments in polymerizations within the nanochannels of porous coordination polymers (PCPs) are covered in this tutorial review. The characteristic features of PCPs are regular structures, controllable channel sizes and shapes, a designable surface functionality, and flexible frameworks, which can be utilized for precision polymer synthesis and specific polymer confinement. This review discusses promising approaches to multiple controls of polymer structures, analysis systems for low-dimensional polymer assemblies and the construction of PCP–polymer nanohybrids, which are strong enticements to researchers in the areas of inorganic, materials and polymer chemistry.