Stiffened plates are common forms used in engineering structures. Extensive research efforts have been devoted to investigating the behavior of stiffened plates under static loading. In the existing models, two issues have not been always appropriately addressed. One is the eccentricity of the stiffeners and the other is the composite action between the plate and stiffeners. In the present paper, static deformation of an eccentrically stiffened plates with partial composite action was analyzed by using the variational approach. In order to investigate the eccentricity and composite action issues, the stiffened plates were idealized as assemblies of plate and beam elements, in such way the stiffeners are discretely connected to the plate elements. Based on the principle of the minimum potential energy, the governing differential equations were derived by using the variational approach with taking into consideration of strain energy of connectors between plate and stiffeners and associated boundary conditions as well. Five displacement functions were defined as double Fourier series to solve the static deflection of simply-supported eccentrically stiffened plates. A relative stiffness factor K with a range of zero to one was introduced to represent the composite action between the plate and stiffeners from no interaction (i.e., K = 0) to rigidly connected (i.e., K = 1). Finally, the proposed energy approach was compared with previously published methods through numerical examples of the plates reinforced by one to fourteen stiffeners in two orthogonal directions.