Blockade of caspase-1 was reported to be a new target for allergic inflammation treatment. Here, we present the effect of linoleic acid (LA), a constituent of Allium hookeri (AH), to alleviate mast cell-mediated allergic inflammation. Pretreatment of LA and AH significantly reduced caspase-1 activation without displaying host cell cytotoxicity in activated human mast cells. IC₅₀ value of LA on caspase-1 activity is 0.014 μM. LA and AH pretreatment effectively regulated increased levels of interleukin (IL)-1β, IL-6, IL-8, thymic stromal lymphopoietin, and tumor necrosis factor on activated human mast cells. Moreover, LA and AH were effective against activations of nuclear factor-κB and mitogen-activated protein kinases in human mast cells. In summary, LA and AH alleviate allergic inflammatory reactions via blocking caspase-1 cascade signaling pathway. These results provide evidence for the anti-allergic inflammatory properties of LA and AH and corroborate its potential use for the treatment and prevention of allergic diseases. PRACTICAL APPLICATIONS: Allium hookeri (AH) is used as traditional food to treat various diseases and contains an essential fatty acid, linoleic acid (LA). LA and AH alleviate mast cell-mediated allergic inflammatory reactions via inhibiting inflammatory mediators. These results provide evidence for the anti-allergic inflammatory properties of LA and AH and corroborate its potential use for the treatment and prevention of allergic diseases.