Bottlebrush polymers possess densely grafted side chains on a long linear backbone. Owing to the distinct structure of these brush polymers, the properties and behavior of polymers tend to differ from common linear polymers. Thus, brush polymers have become a significant focus of polymer research. The synthesis of monodisperse oligomers or linear polymers with defined sequences has been actively developed via the iterative exponential method. However, the synthesis of polymers with high molecular weight (＞50 kDa) has not been achieved. Here, we synthesized the absolutely defined monodisperse brush polymers with monodisperse linear polymer as pendants attached to a monodisperse poly(hydroxy acid) backbone. Owing to the monodisperse backbone chains containing functional groups (alkene- or alkyne-), the functionalization of the backbone chains with various linear side chains could be achieved via Cu(I)-catalyzed alkyne–azide cycloaddition(CUAAC) and thiol–ene “click” chemistry.