The general objective of this study was to examine the determinants of deposit mobilization in Ethiopian private commercial banks, based on balanced panel data collected from audited annual reports of 12 banks and the NBE, covering ten years (2010-2019). The study adopted an explanatory research approach and employed descriptive statistics, correction, and a random effects panel data regression model. The results show statistically significant positive effects of branch expansion, the bank’s profitability (ROA), and the average deposit interest rate on deposit mobilization in private commercial banks in Ethiopia. Conversely, the inflation rate, loan loss provision rate, broad money supply, and liquidity ratio have negative and significant effects. However, capital adequacy and government expenditure have statistically insignificant effects on deposit mobilization. Based on these findings, the government should balance the money supply within the economic circulation and take measures to control inflation, thereby enhancing the deposit mobilization capacity of private commercial banks. Additionally, Ethiopian private commercial banks should develop different mechanisms to encourage customers to save their money.