ABSTRACT A series of novel 3‐alkoxypyrazole‐ and pyrazolone‐fused 1,4‐naphthoquinone derivatives were successfully synthesized through an intramolecular Ullmann‐type cyclization, using 1,4‐dihydroxy‐2‐naphthoic acid as the starting material. Subsequent regioselective N ‐ or O ‐alkylation followed by CAN‐mediated oxidation afforded the desired quinones in moderate to good yields. The molecular structures of the selected N ‐substituted derivatives were unambiguously confirmed by single‐crystal X‐ray diffraction. Preliminary cytotoxicity against RAW264.7 cells revealed that biological activity varied depending on the nature of substitution, with certain compounds exhibiting potent effects (LD 50 < 5 μM). These findings highlight the potential of fused heterocycles as promising lead structures for anticancer drug development.