Abstract <p><b>Objective:</b> The tricyclic carbazole nucleus exhibits various biological activities and is an integral part of many naturally occurring alkaloids and synthetic heterocyclic derivatives. In this work, we further explore a series of carbazole-fused triazole scaffolds. We report the synthesis and anticancer evaluation of a novel 9-((1-phenyl-1<i>H</i>-1,2,3-triazole-4-yl)methyl)-2,3-dihydro-1<i>H</i>-carbazol-4(9<i>H</i>)-one derivative rationally designed by incorporating two active pharmacophoric heterocyclic moieties, <i>viz</i>., carbazole and triazole, in one framework. <b>Methods:</b> All synthesized compounds were characterized by spectral methods, <i>viz</i>., ¹H, ¹³C NMR, and LC-MS. <i>In vitro</i> cytotoxicity of 1,2,3-triazole-linked heterocyclic fragments was investigated using the sulforhodamine B (SRB) assay against the BT474 cell line. <b>Results and Discussion:</b> All synthesized compounds possess an active 1,2,3-triazole moiety in their structure, and the carbazole nucleus has an oxo group at the 4th position. Compounds (<b>Vc–Vg</b>) displayed good anticancer activity with IC₅₀ values ranging from 15.17 to 210.9 μM against the BT474 cell line as compared to the standard drug doxorubicin, which has an IC₅₀ value of 2.32 μM. Molecular docking studies of these molecules revealed good binding interactions with their biochemical target, human epidermal growth factor receptor 2 (HER2), which acts as a networking receptor. <b>Conclusions:</b> Compounds (<b>Vc</b>), (<b>Ve</b>), and (<b>Vg</b>) showed potent cytotoxicity against the BT474 cell line, and molecular docking studies demonstrated strong binding interactions that correlated well with the experimental results.</p>