We review the state of first-principles density functional theory (DFT) modeling of nuclear fuel materials. DFT-based first-principles modeling has emerged as a quantitatively rigorous method that has been widely used to study these materials. The main challenge in DFT modeling of nuclear fuels lies in the f electron nature of actinide materials. DFT + U methods along with regular DFT methods including both non-spin-polarized and spin-polarized treatments are discussed. The review topics include bulk and intrinsic defects properties, stability of fission products, modeling of fission gas (xenon) transport, and non-equilibrium behavior of fission products in uranium dioxide and surrogate materials. In addition, DFT modeling activity in alternative fuel forms including uranium nitride, uranium carbide, and metal fuels is reviewed. Some of the limitations of empirical potential calculations addressed by DFT are also discussed.