Abstract This paper presents the verification of the DeCART2D/CAPP code system for the Very High Temperature Gas-Cooled Reactor (VHTR) analysis with the Prismatic Modular Reactor 200 (PMR-200) benchmark. The McCARD Monte Carlo (MC) code is used to obtain the reference solution. The verification has been performed for the effective multiplication factor (keff) and reactivity coefficients at the levels of fuel compact, fuel block, and full core. Furthermore, the verification of the depletion calculation has been conducted for the fuel block and the verification for the power distribution has been performed at the levels of fuel block, two-dimensional (2D) and three-dimensional (3D) full core. The verification results of DeCART2D, CAPP, and DeCART2D/CAPP are compared systematically against the reference McCARD solutions to demonstrate the VHTR modeling capability and accuracy of the codes. It was successfully shown that the keff errors of the DeCART2D/CAPP code system are smaller than ∼510 pcm, the isothermal temperature coefficient (ITC) errors are smaller than ∼0.66 pcm/K, and the power distribution errors are smaller than 2.80%. It was also shown that the maximum keff errors of DeCART2D fuel block depletion calculations are smaller than ∼460 pcm.