The Main objective of this study is to explore the effect of learning and development on leadership competency development of key leaders in Commercial Bank of Ethiopia. The study covers different middle level managers at Head office, grade III and IV managers at branches, District operation managers and credit appraisal managers. Leadership competency is the dependent variable in the study, while, Training, coaching and mentoring are the independent variables in the study. The methodology employed in this research was explanatory type research on which the effect and relation of factors were tested trough regression and correlation analysis. A total of 126 Questionnaires were distributed to managers at different processes and sub processes across the bank which were categorized under pool two of the career succession management program in CBE. 104 Questionnaires were returned and the response rate is 82.5% .The correlation analysis in the study show that there is a positive relation among variables. The independent variable training is moderately and positively correlated and accounts for (r=.557, P