  We discuss flavor mixing and resultant flavor changing neutral current
processes in the SU(3) \otimes SU(3)_\text{color} gauge-Higgs unification
scenario. To achieve flavor violation is a challenging issue in the scenario,
since the Yukawa couplings are originally higher dimensional gauge
interactions. We argue that the presence of Z_2-odd bulk masses of fermions
plays a crucial role as the new source of flavor violation. Although
introducing brane-localized mass terms in addition to the bulk masses is
necessary to realize flavor mixing, if the bulk masses were universal among
generations, the flavor mixing and flavor changing neutral current processes
are known to disappear. We also discuss whether natural flavor conservation is
realized in the scenario. It is shown that the new source of flavor violation
leads to flavor changing neutral current processes at the tree level due to the
exchange of non-zero Kaluza-Klein gauge bosons. As a typical example we
calculate the rate of K^0 - \bar{K}^0 mixing due to the non-zero Kaluza-Klein
gluon exchange at the tree level. The obtained result for the mass difference
of neutral kaon is suppressed by the inverse powers of the compactification
scale. By comparing our prediction with the data we obtain the lower bound of
the compactification scale as a function of one unfixed parameter of the
theory, which is of {\cal O}(10) TeV, except for some extreme cases. We argue
that the reason to get such rather mild lower bound is the presence of
"GIM-like" mechanism, which is a genuine feature of GHU scenario.
