We investigated the anti-allergic effects of onion, apple, cucumber, ginger, and broccoli mixtures and their bioactive compounds on immunoglobulin E (IgE)-antigen complex-mediated allergic responses in rat basophilic leukemia (RBL)-2H3 cells. Cell viability, formation of reactive oxygen species (ROS), β-hexosaminidase release, and cytokine production were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, 2,7- dichlorofluorescein diacetate assay, β-hexosaminidase assay, and enzyme-linked immunosorbent assay, respectively. Ethanol extracts of onion, apple, cucumber, ginger, and broccoli inhibited the release of β-hexosaminidase in IgE-antigen complex-stimulated RBL-2H3 cells. Plant mixtures (1, 2, and 3) containing different ratios of onion, apple, cucumber, ginger, and broccoli were prepared. The extracts of these mixtures also inhibited the release of IgE-antigen complex-stimulated β-hexosaminidase. High-performance liquid chromatography identified that the main bioactive compounds constituting these extracts were fisetin (Fis), kaempferol (Kae), isoquercitrin and spiraeoside. Fis and Kae dose-dependently inhibited the increase in ROS and β-hexosaminidase levels in IgE-antigen complex-stimulated RBL-2H3 cells. Additionally, Fis and Kae significantly attenuated the production of IgE-mediated pro-inflammatory cytokines, such as interleukin (IL)-4, IL-13, and tumor necrosis factor-alpha. Therefore, mixtures containing Fis and Kae may be used to develop anti-allergic functional foods.