An SO(5)×U(1)×SU(3) gauge-Higgs unification model inspired by SO(11) gauge-Higgs grand unification is constructed in the Randall-Sundrum warped space. The 4D Higgs boson is identified with the Aharonov-Bohm phase in the fifth dimension. Fermion multiplets are introduced in the bulk in the spinor, vector and singlet representations of SO(5) such that they are implemented in the spinor and vector representations of SO(11). The mass spectrum of quarks and leptons in three generations is reproduced except for the down-quark mass. The small neutrino masses are explained by the gauge-Higgs seesaw mechanism which takes the same form as in the inverse seesaw mechanism in grand unified theories in four dimensions.