Using perturbative expansion in terms of powers of the rotation parameter a we construct the axisymmetric and asymptotically flat black-hole metric in the D-dimensional Einstein- Gauss-Bonnet theory. In five-dimensional spacetime we find two solutions to the field equations, describing the asymptotically flat black holes, though only one of them is perturbative in mass, that is, goes over into the Minkowski spacetime when the black-hole mass goes to zero. We obtain the perturbative black-hole solution up to the order O(alpha a(3)) for any D, where alpha is the Gauss-Bonnet coupling, while the D = 5 solution which is nonperturbative in mass is found in analytic form up to the order O(alpha a(7)). In order to check the convergence of the expansion in a we analyze characteristics of photon orbits in this spacetime and compute frequencies of the photon orbits and radius of the photon sphere.