This study examines the impact of political office holders’ performance, economic inequality, and the gap between campaign promises and their fulfilment on the trust deficit in political governance among undergraduate students in Nigerian tertiary institutions, as well as the extent of this trust deficit. The study employed a descriptive survey research design. A multi-stage sampling procedure was utilised to select a sample of 776 undergraduate students from colleges of education, polytechnics and universities in Osun State, Nigeria. Data collection was conducted using an 18-item research instrument titled “Empirical Trust Deficit Survey in Political Governance”. The items were polytomously scored using a five-point Likert scale, ranging from “Strongly Disagree” (SD, scored as 1), “Disagree” (D, scored as 2), “Neither Agree nor Disagree” (NAD, scored as 3), “Agree” (A, scored as 4), and “Strongly Agree” (SA, scored as 5). The instrument was validated by three experts in the field of psychology and educational tests and measurements, administered to a group of 90 tertiary undergraduate students in Osun State, Nigeria, outside the study area, and yielded an internal reliability index of 0.78. The collected data was analysed using descriptive statistics, specifically simple percentages. The results showed that undergraduate students in Nigerian tertiary institutions displayed a level of distrust in political governance due to the perceived low level of performance by political office holders. Additionally, the students neither agreed nor disagreed that economic inequality contributes to their distrust in political governance. Finally, the findings revealed a substantial gap between the campaign promises made by Nigerian politicians and their fulfillment, leading to the erosion of trust among the students. This study recommends, among other suggestions, the implementation of a robust monitoring mechanism in Nigeria to ensure the fulfilment of at least 60% of election campaign promises.