Strain-release cycloaddition chemistry of bicyclo[1.1.0]butanes (BCBs) has emerged as a powerful platform for the construction of saturated bridged frameworks. Despite remarkable advances in formal (2+2), (3+2), and (4+2) annulation reactions, higher-order annulation manifolds of BCBs remain under explored. Herein, we report the first formal (4+3) strain-release annulation of BCBs with indole-derived Michael acceptors, enabling rapid access to azabicyclo[4.1.1]octane-fused indoles. The transform