AIM: Determine the effect of motivational interviewing on emotional authenticity, academic motivation and dispositional optimism among Saudi nursing students. BACKGROUND: Nursing students in Saudi Arabia face various challenges that can impact their emotional authenticity, optimism and academic motivation. As the nursing field grows in Saudi Arabia, maintaining a sustainable nursing workforce and defining the scope of practice present challenges. Therefore, investigating feasible interventions to promote the well-being and success of Saudi nursing students is crucial. DESIGN: A randomized controlled trial research design was followed. Each study participant was randomly assigned 1:1 to either the intervention group or the control group. METHOD: The study involved 70 nursing students, who were randomly divided into an intervention group (n = 35) and a control group (waiting list) (n = 35). Pre-tests and post-tests were administered to evaluate the impact of motivational interviewing program implemented between April 2024 and mid-August 2024. RESULTS: Following the intervention, the study group demonstrated substantial enhancements in Authenticity Inventory scores, Academic Motivation Scale scores and dispositional optimism, with p-values consistently below 0.001 and large effect sizes ranging from 0.650 to 0.937. Comparing to the control group, the study group showed marked increases in positive optimism and decreases in negative optimism, alongside a reduction in amotivation. CONCLUSION: The study demonstrates that the motivational interviewing intervention led to significant improvements in various aspects of emotional authenticity, including self-awareness, unbiased emotional processing and authentic behaviors and relational orientations. Additionally, the study group exhibited substantial increases in intrinsic and extrinsic academic motivation and a reduction in amotivation.