Quantum coherence in the excitonic energy transfer can live for up to several hundred femtoseconds despite the strong coupling to high-temperature environmental fluctuations. Studying a simple donor–acceptor pair shows that typical environmental fluctuations in light-harvesting complexes are slower than the electronic transfer dynamics and, thus, systematically support quantum coherence, which allows the coherence to live on timescales comparable with the total transfer time. Thus, long-lived quantum coherence is a result of the constructive fluctuations spectra, which the chromophores experience. Also, non-Markovian effects of such slow environmental fluctuations support and even generate long-lived quantum entanglement. Interpair dipole–dipole coupling allows for the generation of entanglement out of separable initial states and shows death and revivals of entanglement on timescales relevant for excitonic energy transfer. Even without interpair coupling, entanglement is generated by a slowly fluctuating environment, which is a result of spatial correlations of the environmental fluctuations over different chromophore sites. Thus, in biomolecular environments as typical for chromophores in light-harvesting complexes, entanglement is long-lived and is generated by interpair couplings or spatially correlated fluctuations.