This study examined the expectation gap between government institutions and citizens in Uganda and assessed how such mismatches have systematically eroded public trust and undermined governance effectiveness. Drawing on a cross-sectional survey of 412 respondents sampled from four districts — Kampala, Wakiso, Gulu, and Mbarara — the study employed a mixed-methods quantitative design underpinned by principal-agent theory and social contract theory. Univariate analysis revealed that 71.8% of respondents perceived a significant gap between what government promised and what was delivered, with only 28.2% expressing satisfaction with public service outcomes. Bivariate correlation analysis demonstrated statistically significant negative relationships between the expectation gap and trust in government institutions (r = -0.623, p < 0.001), citizen engagement (r = -0.541, p < 0.001), and perceived governance quality (r = -0.587, p < 0.001). Structural Equation Modelling (SEM) confirmed that the expectation gap directly reduced trust (β = -0.48, p < 0.001), which in turn diminished citizen participation (β = -0.39, p < 0.001) and perceived service delivery quality (β = -0.42, p < 0.001), with the model explaining 54.3% of variance in governance outcomes. Key drivers of the expectation gap included poor communication of government plans (M = 4.31/5.00), inconsistency in policy implementation (M = 4.18/5.00), and absence of accountability mechanisms (M = 4.05/5.00). The study concluded that bridging the expectation gap requires deliberate institutional reforms, transparent communication strategies, and robust citizen feedback mechanisms. It recommended that the Government of Uganda institutionalise participatory policy formulation processes, strengthen independent oversight bodies, and invest in civic education to calibrate citizen expectations to realistic governance capabilities.