The continuous antigenic drift of zoonotic H7 avian influenza viruses remains a significant global public health threat. While monoclonal antibodies (mAbs) targeting the hemagglutinin (HA) head offer potent neutralization, their efficacy is often undermined by rapid viral escape. In this study, we systematically mapped the antigenic architecture of the H7 HA head domain using a panel of 30 murine mAbs. By integrating epitope mapping with longitudinal evolutionary analysis of over 2,500 isolates, we identified highly conserved, functionally constrained residues, specifically G70, G132, N167, and M173, that remained nearly invariant over decades. Leveraging these insights, we engineered a chimeric bispecific antibody (BsAb-H7) to simultaneously engage two distinct, non-overlapping conserved epitopes. BsAb-H7 demonstrated broad neutralization breadth across divergent H7N9, H7N7, and H7N3 subtypes in vitro and exhibited a superior in vivo pharmacokinetic profile. In lethal murine challenge models, BsAb-H7 provided robust prophylactic and therapeutic protection against heterologous H7N7 infection. Notably, localized intranasal administration significantly outperformed systemic delivery by accelerating viral clearance and resolving pulmonary immunopathology during delayed intervention windows. These results demonstrate that bispecific targeting of conserved HA epitopes effectively enhances antiviral breadth and limits immune escape, providing a promising strategy for the development of broadly protective therapeutics against rapidly evolving H7 influenza viruses.