In accidents involving fire, vehicle designers account for structural effects from degradation of mechanical properties while also ensuring that interior temperatures remain within survivable bounds. Simulating carbon fiber reinforced polymer (CFRP) structures in extreme environments, such as fire exposure, is challenging because of how the mechanical and thermal responses interact, so a multiphysics simulation is required to accurately capture the material response. The present investigation discusses the development of a simulation approach that incorporates mechanical and thermal behavior of a CFRP coupon with an applied heat flux representing an aircraft fire. Sandia National Laboratories’ SIERRA Arpeggio software was used to perform the multiphysics simulations, which allows for a two-way coupling of the mechanical and thermal simulations. The simulated thermal and mechanical response were compared to existing experimental data from the literature, and simulation results showed improved agreement with experimental data when including coupled thermomechanical interactions. Further assessment of the simulation results shows that accurately modeling the effects of delamination is a key factor in capturing both the mechanical and thermal response during heating of the CFRP structure.