The aim of this study was to investigate the mediating role of self-efficacy in decision making between the relationship of workload, work control and decision-making styles. Although the decision-making process seems basically the same for every individual, it is different for each individual in terms of content. The reason for this is the methods used by individuals in making decisions and their approach to problems are different. The data was gathered from 252 government officials, chiefs, branch managers and heads of the departments of the Republic of Turkey. The data was analysed with structural equation model. The results indicate that there was a negative relationship between the level of workload and vigilant decision-making style, and a positive relationship with buck-passing, procrastination, and hypervigilance decision making styles. On the other hand, a positive relationship between work control and vigilance decision-making style, and a negative relationship between buck-passing, procrastination and hypervigilance decision-making styles were observed. At the same time, there was a negative relationship between workload and self-efficacy in decision-making, yet a positive relationship was found with work control. In addition, a full mediating role in the relationship between workload in decision-making self-efficacy, work control, vigilant, buck-passing, and procrastination decision-making styles; a partial mediating role was found in the relationship between workload and hyper vigilant decision-making style in work control were found separately. The results were interpreted with the light of literature and lead to develop practical suggestions for managers and employees.