Both unitary chiral theories and lattice QCD simulations show that the DK interaction is attractive and can form a bound state, namely, D^*_{s0}(2317). Assuming the validity of the heavy antiquark–diquark symmetry, the Xi _{cc}{bar{K}} interaction is the same as the DK interaction, which implies the existence of a Xi _{cc}{bar{K}} bound state with a binding energy of 49-64 MeV. In this work, we study whether a Xi _{cc}Xi _{cc}{bar{K}} three-body system binds. The Xi _{cc}Xi _{cc} interaction is described by exchanging pi , sigma , rho , and omega mesons, with the corresponding couplings related to those of the NN interaction via the quark model. We indeed find a Xi _{cc}Xi _{cc}{bar{K}} bound state, with quantum numbers J^P=0^-, I=frac{1}{2}, S=1 and C=4, and a binding energy of 80–118 MeV. With the same formalism, we find that the Xi _{cc}bar{Xi }_{cc}{bar{K}} system also binds, yielding a I(J^P)=frac{1}{2}(0^+) state and a frac{1}{2}(1^+) state with binding energies of 56–68 MeV and 56–67 MeV respectively. As a byproduct, we show the existence of a NN{bar{K}} state with a binding energy of 35–43 MeV, consistent with the results of other theoretical works and experimental data, which serves as a consistency check on the predicted Xi _{cc}Xi _{cc}{bar{K}} bound state.