Long-wavelength luminescence from boron-based cations is typically hindered by both intrinsic instability and pronounced non-radiative decay. Now a triadic design that integrates a non-Kekulé polycyclic aromatic hydrocarbon framework, a charge-localizing carbodicarbene ligand and counterion-directed assembly enables stable borenium ions with tunable red-to-near-infrared emission in the solid state.