This study examined the relationship between tax administration and tax revenue performance at the Kampala Capital City Authority (KCCA), Uganda. Local revenue is critical to the capacity of city authorities to deliver services and pursue development, and the effectiveness of tax administration is a principal determinant of how much revenue is actually raised. The study investigated how taxpayer registration, tax assessment, tax collection and enforcement, and taxpayer education relate to tax revenue performance. A cross-sectional survey design with a mixed-methods approach was adopted, and data were collected from 170 respondents comprising KCCA revenue officials, tax collectors, and registered taxpayers using structured questionnaires and interviews. Descriptive statistics, Pearson correlation, and structural (path) analysis were used. The results revealed a strong positive and significant relationship between tax administration and tax revenue performance (r = 0.69, p < 0.01), with the tax administration dimensions jointly explaining 67.0% of the variance in revenue performance (R² = 0.670). Tax collection and enforcement (β = 0.33) and tax assessment (β = 0.29) emerged as the strongest path predictors. The study concludes that effective tax administration significantly enhances tax revenue performance and recommends strengthening collection and enforcement, improving assessment, and expanding taxpayer education.