Oxidative stress due to overproduction of reactive oxygen species (ROS) plays a major role in inflammation, cancer, and neurodegenerative disorders. In this study, 60 chalcone derivatives with fluorine (F), trifluoromethyl (CF3), trifluoromethoxy (OCF3), chlorine (Cl), and bromine (Br) in ring A and with or without hydroxy (OH) in ring B were designed, synthesized, and screened for inhibitory activity against lipopolysaccharide (LPS)‐stimulated ROS production in RAW 264.7 macrophages. Structure–activity relationship study revealed the importance of a hydroxyl moiety in ring B for enhancing inhibitory activity of ROS production. Furthermore, a hydroxyl group at the ortho‐position is more essential for inhibition of ROS production followed by meta‐ and para‐positions. Among all, compound 27 that contains para‐chlorine moiety in ring A and ortho‐hydroxy in ring B displayed the strongest inhibitory activity (IC50 = 3.42 μM) against LPS‐stimulated ROS production in RAW264.7 macrophages.