We propose an uncertainty-motivated morality hypothesis whereby individuals behave more morally under uncertainty than under certainty, as if moral behavior will yield a better outcome as the result of uncertainty. We test this hypothesis in a series of experiments and observe that individuals are more honest under uncertain situations than degenerate deterministic situations. We further show that this pattern is best explained by our hypothesis and is robust and generalizable. These results are incompatible with standard models and consistent with quasi-magical thinking and related notions. Our study contributes to the literature of decision-making under uncertainty and with moral considerations.