Significance Fluorescence imaging, a central pillar of medical and fundamental research, is hampered by stochastic blinking, limited photon budgets, and phototoxicities of organic fluorophores. Here, we use quantum chemical calculations and targeted synthetic strategies to tune the Baird aromatic triplet-state energy of cyclooctatetraene to enhance its capacity to mediate intramolecular triplet−triplet energy transfer with distinct organic fluorophores spanning the visible spectrum. By tuning the efficiency of the self-healing mechanism, we generate cyanine-class fluorophore derivatives with improved intrinsic brightness and photostability, and reduced reactive oxygen species generation. We leverage these advances to extend the time scale of camera-based, single-molecule imaging techniques, including Förster (fluorescence) resonance energy transfer methods, to the kilohertz regime in fully oxygenated physiological buffers.