Monoclonal antibodies (mAbs) are critical tools for elucidating viral evolution, informing vaccine design, and developing therapeutics. Here, we report the first porcine mAbs directed against H3, H5, and H7 influenza virus haemagglutinins. Following infection or sequential immunisation, pigs generated strain-specific and broadly reactive antibodies targeting both head and stem epitopes. Importantly, an H3 mAb (H3-57) was specific to the egg-adapted L194P mutation, implicated in reduced human vaccine effectiveness. H5 and H7 immunisations induced neutralising antibodies, including cross-group stem mAbs reactive with H1, H3, and H5 HAs. Fc-mediated activity correlated with binding strength rather than epitope location. These findings demonstrate that pigs can mount antibody responses similar to humans, recognising conserved stem epitopes and adaptive head mutations. The porcine mAbs provide powerful new tools for dissecting influenza immunity, guiding vaccine design, and improving pandemic preparedness using a physiologically relevant large-animal model.