Carbon‐chain dendritic polymers hold unique properties and promising applications. However, synthesizing carbon‐chain dendrimers, beyond conjugated ones, remains a challenge. Here, we described the use of the iterative single unit monomer insertions (SUMIs) technique for synthesizing 2.5 generation partial carbon‐chain dendrimers (G2.5), utilizing bismaleimide as the core, a maleimide‐trithiocarbonate conjugate as the branching unit, and indene as the spacer unit, following a divergent growth strategy. The optimized conditions for synthesizing the maleimide‐trithiocarbonate branching unit were a bismaleimide to trithiocarbonate ratio of 5:1 and a reaction time of 30 minutes. The structures were verified using 1H NMR, gel permeation chromatography, and MALDI‐TOF MS. A four‐arm star polymer was then synthesized using the G2.5 as the core. This synthesis of a partial carbon‐chain dendrimer establishes a foundational step towards creating all carbon‐chain ones and may open new application avenues in material science.This article is protected by copyright. All rights reserved