In the framework of linear dynamic analysis of bladed disks, the intentional mistuning has been identified as a technological way for reducing the sensitivity of the forced response of bladed disks to mistuning induced by the manufacturing tolerances and by the small variabilities of mechanical properties. The role played by the geometrical nonlinearities(Capiez-Lernout 2015) and dry friction in the dynamics of bladed disk has recently received a particular attention. In this paper, we present an analysis of the effects of geometrical nonlinearities on an intentional mistuned bladed disk. For that, a simplified bladed disk made up of 24 blades is defined for which a computational model is constructed by using the finite element method. Two different blades are used and allow for defining a pattern with 22 blades of type 1 and 2 blades of type 2. A projection basis is computed and a linear and a nonlinear reduced-order model (ROM) are constructed for the defined bladed disk. A comparison of the responses of the mistuned bladed disk computed with the linear ROM and with the nonlinear ROM is performed in order to analyze the role played by the nonlinearities on the intentional mistuning. The numerical results obtained show the significant influences of the nonlinear geometrical effects in the dynamical responses.