Pursuing our effort for developing effective inhibitors of the cancer-related hCA IX isoform, here we describe the synthesis of novel benzofuran-based carboxylic acid derivatives, featuring the benzoic (<b>9a</b>-<b>f</b>) or hippuric (<b>11a,b</b>) acid moieties linked to 2-methylbenzofuran or 5-bromobenzofuran tails via an ureido linker. The target carboxylic acids were evaluated for the potential inhibitory action against hCAs I, II, IX, and XII. Superiorly, benzofuran-containing carboxylic acid derivatives <b>9b</b>, <b>9e</b>, and <b>9f</b> acted as submicromolar hCA IX inhibitors with KIs = 0.91, 0.79, and 0.56 μM, respectively, with selective inhibitory profile against the target hCA IX over the off-target isoforms hCA I and II (<i>SI</i>s: 2 to >63 and 4-47, respectively). Compounds <b>9b</b>, <b>9e</b>, and <b>9f</b> were examined for their antiproliferative action against human breast cancer (MCF-7 and MDA-MB-231) cell lines. In particular, <b>9e</b> displayed promising antiproliferative (IC<sub>50</sub> = 2.52 ± 0.39 μM), cell cycle disturbance, and pro-apoptotic actions in MDA-MB-231 cells.