Significance Fluorescent polymers play an important role in bioimaging due to their improved brightness, inertness to microenvironment, and good biocompatibility. In this article, we used tetraphenylene (TPE) derivatives that give strong fluorescence emission in an aggregated state as fluorophores and synthesized fluorescent polymers via the covalent linkage of TPE-based rhomboidal Pt(II) metallacycles. Due to the integration of covalent linkage-induced aggregation of the monomers, the aggregation-induced emission character of TPE derivatives together with Pt(II)-based metal−ligand interactions, these polymers exhibit enhanced emission compared with their corresponding precursors, making them applicable as excellent cell imaging agents. Considering the potential anticancer activity of rhomboidal Pt(II) metallacycles, these polymers may serve as theranostic agents for both bioimaging and cancer therapy.