Macrocyclic supramolecular coassembly is the current research hotspot for tumor treatment. Herein, we report a multivalent supramolecular coassembly strategy, which not only acquires long-time phosphorescent labeling of mitochondrial aggregation but also strongly enhances chemotherapeutic efficiency against drug-resistant tumors. The mitochondrial aggregation depends on cucurbit[8]uril-mediated cross-linkage of the hyaluronic acid polymer grafted by 4-bromophenylpyridium and mitochondrion-targeting peptide (HABMitP) residing on the mitochondria, taking advantage of the 2:1 homoternary host-guest complexation between cucurbit[8]uril and 4-bromophenylpyridium with an extraordinary binding constant (6.24 × 10 12 M -2 ). In cisplatin-resistant MCF-7 tumor cells, the assembly induced mitochondrial aggregation substantially enhances the antitumor efficiency of cisplatin, with the ratio of apoptotic cells increasing from 43% to 96% compared to treatment with cisplatin alone, and thoroughly inhibits tumor growth in vivo . This study provides a novel way for biological phosphorescent imaging and treatment of drug-resistant cancers.