In summary, a polymer density functional theory (PDFT) is rigorously extended to neutral and charged PB systems. Specifically, the hard-core interactions and direct Coulomb interactions are coupled with the physical constraints of grafted PBs. Furthermore, the PDFT is calibrated via the density profiles of the monomers and counterions provided by the MC and MD simulations. The comparison results show that the density profiles of the neutral and weakly charged PBs agree excellently with the results from MC and MD simulations, although there is a little difference between the predictions from PDFT and MD simulations in the cases with fully charged PBs. This subtle deviation may be caused by the model differences in PDFT and MD simulations as well as the lack of ion-ion electrostatic correlations in the PDFT. Altogether, beyond providing clear insight into the significant consequences of the grafting behavior, an accurate and reliable theoretical method is proposed for revealing the interfacial microstructure of neutral and charged PBs in the molecular level. We believe that this theory can be used to tune the interfacial functional layer in a reasonable way, which is benefit for many applications such as colloidal stabilization, ionic separation, and energy-storage devices.