We report the synthesis, biological evaluation, and structural study of a series of substituted heteroaryl-pyrazole carboxylic acid derivatives. These compounds have been developed as inhibitors of specific isoforms of carbonic anhydrase (CA), with potential as prototypes of a new class of chemotherapeutics. Both X-ray crystallography and computational modeling provide insights into the CA inhibition mechanism. Results indicate that this chemotype produces an indirect interference with the zinc ion, thus behaving differently from other related nonclassical inhibitors. Among the tested compounds, 2c with Ki = 0.21 μM toward hCA XII demonstrated significant antiproliferative activity against hypoxic tumor cell lines. Taken together, the results thus provide the basis of structural determinants for the development of novel anticancer agents.