We propose a novel measure of income-related uncertainty, grounded in Izhakian's (2020) expected-utility framework of Knightian uncertainty, and examine its effect on international migration using a panel of European countries from 2007-2022. We find a robust negative association between income uncertainty and net immigration inflows. The effect is stronger in high-income countries, consistent with existing empirical evidence that uncertainty aversion amplifies the deterrent impact of uncertainty when the expected probability of favorable outcomes, i.e., the likelihood of achieving higher income in our migration context, is higher. Our measure outperforms broader proxies such as the Economic Policy Uncertainty and Macroeconomic Uncertainty indexes, highlighting its value in capturing distributional income uncertainty directly faced by migrants and offering a more behaviorally relevant basis for understanding how uncertainty shapes international migration.