The millipede genus Mandarinopus Verhoeff, 1933 (Sulciferini, Paradoxosomatidae), endemic to western China, currently comprises five species. Its taxonomic delimitation from Kronopolites Attems, 1914, remains controversial because of morphological similarity and overlapping distributions. Previous studies relying exclusively on morphological characters yielded ambiguous results. To clarify the taxonomic status of Mandarinopus, we conducted an integrative taxonomic study using topotypic specimens of all species of Mandarinopus and representative species of Kronopolites. Phylogenetic analyses based on four genetic markers (COI, 16S, 18S, and 28S rRNA) reveal that Mandarinopus is polyphyletic and deeply nested within Kronopolites. Notably, the type species of both genera form a strongly supported sister pair. Morphological re-examination demonstrates that the diagnostic characters previously used to distinguish the genera, specifically gonopodal features, are continuous and lack clear boundaries. Consequently, we formally propose Mandarinopus Verhoeff, 1933, as a junior synonym of Kronopolites Attems, 1914, transferring all valid Mandarinopus species to Kronopolites. Additionally, based on morphological and molecular evidence from topotypic material, we propose Kronopolites rugosus Golovatch, 2013, as a junior synonym of Kronopolites corticinus (Attems, 1936).