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Alkyne polycyclotrimerizations have become efficient synthetic tools for constructing hyperbranched polyphenylenes. However, the polycyclotrimerization reactions of internal alkynes are rarely reported. Herein, we present the first example of RhCl 3 -catalyzed polycyclotrimerization of activated internal diynes to prepare hyperbranched polymers. The polymerization reactions of diphenylpropiolates (1a−c) were performed in toluene under reflux in the presence of RhCl 3 •3H 2 O and N,N-diisopropylethylamine (DIPEA), affording soluble hyperbranched poly-(triphenylbenzoate)s (hb-PTPBs), hb-P1a−c, with high molecular weights (up to 187000) and high regioregularities (fraction of 1,2,4-triphenylbenzoate isomer up to 88.2%) in satisfactory yields. The degree of branching of hb-P1a was determined to be 0.73. The resultant hb-PTPBs are thermally stable, with 5% weight loss temperatures higher than 330 °C. The hb-PTPBs are weakly emissive in their dilute solutions but become intensively emissive upon aggregate formation, showing aggregation-induced emission features.