The rotation of the polarization plane of a polarized light beam through a hybrid aligned liquid‐crystal cell is described, by taking into account the joint effect of the weak anchoring and of the flexoelectricity in the presence of an electric field normal to the initial deformation plane and smaller than Fre´edericksz’ threshold [H. Kelker and R. Hatz,HandbookofLiquidCrystals(Chemie, Weinheim, 1980), pp. 160–188]. Such a rotation is shown to be proportional to the square root of the difference between the actual and the critical thickness of the cell in the case of small thicknesses (which are interesting in the display technology) whereas in the case of larger thicknesses the same relation deduced by Durand’s group for strong anchoring is obtained.