The mental health of international students has become a concern, as they face high levels of psychological distress. We designed a five-week acceptance and commitment therapy (ACT) workshop with two additional individual assessment meetings. The intervention aimed at helping international students attending a Finnish university to reduce their symptoms of stress, depression, and anxiety, and enhance skills of psychological flexibility. The post-assessment was conducted seven weeks after the pre-measurement. Using data from 53 participants, an evaluation indicated that statistically and clinically significant reductions in symptoms were observed, and the workshop was well received. Regression analyses revealed that changes in psychological inflexibility, mindfulness, and value-based living acted as predictors of change in symptoms. Furthermore, changes in these psychological skills predicted changes in different kinds of distress. This study suggests that a brief group intervention might be a feasible alternative for enhancing the psychological well-being of international students.