  We present a field theoretical model unifying grand unified theory (GUT) and
brane world scenario. As a concrete example, we consider $SU(5)$ GUT in 4+1
dimensions where our 3+1 dimensional spacetime spontaneously arises on five
domain walls. A field-dependent gauge kinetic term is used to localize massless
non-Abelian gauge fields on the domain walls and to assure the charge
universality of matter fields. We find the domain walls with the symmetry
breaking $SU(5)\to SU(3)\times SU(2)\times U(1)$ as a global minimum and all
the undesirable moduli are stabilized with the mass scale of $M_{\rm GUT}$.
Profiles of massless Standard Model particles are determined as a consequence
of wall dynamics. The proton decay can be exponentially suppressed.
