Tethered polymers have several industrial applications in colloid stabilization, adhesives, lubricants, modification of surface hydrophobicity, microfluidic devices, and biophysics. Two important aspects have major impact on the process and design of these applications: structure of tethered polymers at the surface/interface and force of interaction between the polymer tethered surfaces/interfaces. We extend our classical density functional theory (DFT) for complex inhomogeneous fluids known as interfacial statistical associating fluid theory (iSAFT) to investigate the structure and interaction force of these tethered polymers. Depending upon the number of polymer chains tethered to the surface (grafting density) and the quality of the solvent, these polymer chains can either stretch away from the surface or collapse onto it. And the force can be either attractive or repulsive. With iSAFT we will be able to explicitly account for the compressibility and difference in the segment sizes of the tethered and solvent polymer chains, which are missed by the previous scaling and self consistent field (SCF) theories for tethered polymers.