In contrast to the familiar Kirchoff approach, a simple, consistent, shear flexible model for the stability analysis of stiffened panels has been developed in the context of hybrid mixed technique. This model is composed of a quadrilateral plate element, as well as its complementary skeletal grid element. The formulation is based on the Hellinger/Reissner mixed variational principle with independently assumed displacement and strain fields. The proposed model has been utilized to develop a general finite element code for determination of critical buckling stresses of stiffened panels for any case of in-plane loadings and boundary conditions. The effectiveness and practical usefulness of this model have been demonstrated by a variety of numerical results for practical applications. In particular, design curves for buckling stresses of simply supported rectangular panels with central cut-outs and lateral stiffeners have been developed under in-plane load-type. These curves provide a valuable insight into the behavior of stiffened panels and could be useful for design codes.