The study investigates the causal relationship between income inequality and health outcomes in Nigeria using Toda Yamamoto from 1990-2024. The underpinned theoretical framework for the work is based on the Wilkinson income inequality health hypothesis. Life expectancy, infant mortality rate, under-five mortality rate, and maternal mortality rate was used to measure health outcomes and income inequality was measured by gini coefficient. The data were obtained from United Nation database and World Bank. Toda Yamamoto causality test was used to examine the causal relationship among measures of health outcomes and income inequality in Nigeria. The findings revealed that life expectancy, infant mortality rate, and maternal mortality rate had a unidirectional causal relationship with income inequality in Nigeria. Also, the result shows that under-five mortality has no causal relationship with income inequality in Nigeria. The study recommends government should implement policies that promote equitable distribution of income such as cash transfers and job creation programs. There is need for government to increased healthcare funding and expand health insurance programs that could improve access to quality healthcare for low-income individuals