Background The psychological well-being of university students is an important factor in successfully coping with the demands of academic life. This study aimed to assess the impact of a peer-led intervention of mental health promotion combined with coping-strategy-based group workshops on mental health awareness and help-seeking behavior among university students in Hong Kong. Method A mixed-method concurrent design was used for this study. Quantitative data, based on one-group pretest-posttest design, were collected using Mental Health Knowledge Schedule Questionnaire to assess mental health awareness, and Attitude Towards Seeking Professional Help Questionnaire-Short Form to examine help-seeking behavior of university students from The Hong Kong Polytechnic University. Qualitative data were collected from written post-activity reflections and focus group discussions which were thematically analyzed. Results A total of 62 university students (mean age: 23.2 ± 5.1 years) were included in this study. Mental health awareness was significantly improved (p = 0.015, 95% Confidence Interval of − 2.670, − 0.297) after program implementation. Help-seeking behavior mean score increased from pretest to posttest, however, no significant difference was observed (p = 0.188, 95% CI = − 1.775, 0.355). Qualitative analysis revealed that the program helped participants learn about coping strategies to help themselves and others with mental health challenges. Conclusions The peer-led intervention provided a positive impact through increased mental health awareness and knowledge of coping strategies on self-help and helping others among university students. Further study could focus on the impact of the program when applied regularly throughout the entire academic year.