In this paper, we investigated the 4f–5d transition energy of Ce 3+ in various fluoride hosts based on the first-principles discrete-variational Dirac–Slater (DV-DS) calculations using Slater's transition-state theory. Especially, we focused on the lowest energy peak (1st peak) of 4f–5d transition for Ce 3+ impurities. As the host crystals, we adopted the 15 fluorides, for which the experimental data of the lowest energy peak (1st peak) in 4f–5d transitions were available from literature except for NaMgF 3 and BaMgF 4 . A high correlation between the experimental 1st peak energies and the theoretical ones was obtained which suggests a possibility to predict the 4f–5d transition energy of Ce 3+ in various fluoride hosts using the first-principles calculation.