This study investigates the effects of the five-factor personality traits (FFPTs) of school administrators on decision-making processes. The research was conducted using one of the quantitative research approaches, the relational survey model. The research sample comprised 363 managers working in Istanbul during the academic year of 2020-2021, of which 133 were female, and 230 were male. Five-Factor Personality Traits Scale and Melbourne Decision-making Scale were used as data collection tools. Neuroticism, one of the subdimensions of the Big Five Inventory, was found to negatively influence self-esteem in decision-making, whereas extroversion, conscientiousness, openness, and agreeableness positively influenced self-esteem in giving. Neuroticism, one of the sub-dimensions of the Big Five Inventory, positively influenced attentive, avoidant, delaying, and frightened decision-making styles. In contrast, extroversion, conscientiousness, openness, and agreeableness negatively influenced these decision-making styles.