In this work, a novel class of diblock polymer ligands, poly(ethylene oxide)-block-polystyrenes end-functionalized with 2,6-bis(benzimidazol-2'-yl)pyridine (bzimpy), have been synthesized and their coordination reactions with K2PtCl4 have created platinum(II)-containing diblock copolymers. They emit red phosphorescence in both THF-water and 1,4-dioxane-n-hexane mixed solvents, arising from Pt(II)···Pt(II) and/or π-π stacking interactions between the planar [Pt(bzimpy)Cl]+ units. Correspondingly, the block copolymers demonstrate a solvent-tunable self-assembly behavior to controllably generate vesicles and worms with core-shell-corona architectures. In these hierarchical nanostructures, the planar [Pt(bzimpy)Cl]+ blocks are associated together to form cores driven by Pt(II)···Pt(II) and/or π-π stacking interactions. Such cores are completely isolated by PS shells, which are further encapsulated by PEO coronas. It should be highlighted here that diblock polymers as polymeric ligands are coupled with phosphorescence platinum(II) complexes, representing a novel approach to create functional metal-containing polymer materials with hierarchical architectures.