We derive a nonequilibrium fluctuation-dissipation relation for bosonic correlation functions from holography in the classical gravity approximation at strong coupling. This generalizes the familiar thermal fluctuation-dissipation relation in the absence of external sources. This also holds universally for any nonequilibrium state which can be obtained from a stable thermal equilibrium state in perturbative derivative (hydrodynamic) and amplitude (nonhydrodynamic) expansions. Therefore, this can provide a strong experimental test for the applicability of the holographic framework. We discuss how it can be tested in heavy-ion collisions. We also make a conjecture regarding multipoint holographic nonequilibrium Green's functions. © 2013 American Physical Society.