• PmTNF is a novel TNF gene in pearl oysters with conserved TNF domain and constitutive expression, highest in gills.
• PmTNF expression is modulated by pathogen stimuli and nucleus insertion surgery, indicating its role in immune response.
• RNA interference of PmTNF suppresses NF-κB pathway genes, while recombinant PmTNF upregulates them and enhances antioxidant enzyme activities.
• PmTNF is a key regulator of pearl oyster immunity, linking NF-κB signaling and antioxidant defense.