The influences of hydrostatic pressure combined to the size effect on the behavior of the exciton in 2D GaN/AlN quantum ultra‐thin disk, on the binding energy and optical absorption coefficient are investigated. Our approach is performed in the framework of effective mass theory and by using a variational method with a robust trial wave function and taking into account the dependence of the size, the dielectric constant and the effective masses on the pressure. Variations of the excitonic binding energy, optical transition energy are determined according to hydrostatic pressure. The results of our numerical calculations show that the applied pressure favors the electron–hole attraction leading to an increase of the ground state exciton binding energy, and causes a shift of the absorption coefficient toward high energies (blue shift).