This study examined the impact of the adoption of International Financial Reporting Standards (IFRS), with emphasis on IFRS 9, on the financial performance of Stanbic Bank Uganda. A time-series case study design used a quarterly series from the first quarter of 2012 to the fourth quarter of 2024 (52 quarters), analysed with descriptive statistics, Pearson correlations, group comparisons, multiple linear regression with autocorrelation-robust standard errors, and binary logistic regression, supported by diagnostic tests. Return on assets (ROA) averaged 3.74 per cent. ROA fell to a mean of 2.73 per cent in the 2018 transition year, 1.01 percentage points below the pre-IFRS 9 mean, and recovered to a mean of 3.91 per cent after 2018. In regression, the transition year lowered ROA by 0.68 percentage points, the post-transition period raised it by 0.55 points relative to the pre-IFRS 9 period, and the COVID-19 period lowered it by 0.56 points; the model explained 58.1 per cent of the variance. In the logistic model, the post-transition period reduced the odds of a below-par return by 96 per cent. The study concluded that IFRS 9 imposed a temporary firsttime adoption cost on profitability through higher expected credit loss provisioning but had no lasting negative effect, and that it was associated with improved stability thereafter. Recommendations addressed transition planning, provisioning models, disclosure and capital management.