Significance Photosynthetic organisms evolved their light-harvesting antenna complexes to optimize energy transfer. It was recently shown that the redox environment can tune the mixing of electronic and vibrational states to steer energy through different pathways of a pigment–protein complex. Quantum beating signals in the spectra of pigment–protein complexes have been used to probe the excited-state dynamics within the complexes, but the microscopic dynamics that generate these signals and their role in promoting energy transfer are not fully understood. Here, we show that the redox environment that tunes energy transfer similarly tunes the quantum beating signals in the same complex. We find that the beats report on excited-state vibrations that maintain coherence through the vibronically enhanced energy transfer process.