The Landauer-Böttiker approach formulated in the framework of the spin-polarized surface Green function technique and the tight-binding linear muffin-tin orbital method is used to study the magnetotransport in the presence of the domain walls (DW) from first principles. Our approach allows to treat both the ballistic and the diffusive regime of the DW transport on equal footing. The effect of disorder is included in terms of lateral supercells confined to individual atomic layers within a DW. In this paper we apply the method to fcc(001)-based DW of elemental ferromagnets.