This cross-sectional study explored the relationship between emotional regulation, the Big Five personality traits, and happiness among 411 nursing students in Saudi Arabia, with an average age of 19.6. The Oxford Happiness Inventory, Big Five Personality Test, and Emotional Regulation Inventory were used as research instruments through self-administered questionnaires. The findings revealed that nursing students had a moderate level of happiness (mean = 3.5), with students in their third year being happier than those in their first year. The most expressed personality traits among the students were agreeableness (79%) and conscientiousness (69%). Furthermore, the study discovered that cognitive reappraisal was higher among single students and those aged 19 or younger. Finally, the study identified extraversion, agreeableness, conscientiousness, neuroticism, and cognitive reappraisal as predictors of happiness level (adjusted R[superscript 2] = 57%). The study suggests that improving emotional regulation could enhance the happiness and well-being of nursing students.