Abstract Background Refugees encounter various risk factors that can affect their mental health throughout the migration process. However, while most studies focus on mental health challenges at the time of resettlement, only a few explore these changes over an extended period. This study aims to explore changes in mental health among Syrian refugees in Norway and to identify influencing factors. Methods This is a prospective cohort study using data from CHART and Integration for Health studies, which followed Syrian refugees granted settlement in Norway. Data collection took place in Lebanon between 2017-2018 (baseline), and at one- and four-years post-arrival in Norway. Assessments for anxiety/depression and post-traumatic stress disorder (PTSD) were conducted using the Hopkins Symptom Checklist (HSCL-10) and the Harvard Trauma Questionnaire, respectively. Mixed-effects logistic regression analyzed temporal changes, with results presented as odds ratio (OR) with 95% confidence intervals (CI). The study also explored the effect modification of outcomes by the following baseline factors: age, gender, education. Results A total of 132 participants were included in all three data collection points. There was a decrease in the proportion of participants reporting anxiety/depression (from 30% to 28%, OR 0.1, 95% CI 0.1 - 0.2) four years post-settlement. The proportion of participants reporting PTSD symptoms decreased one year after settlement (from 4% to 3%, OR 0.3, 95% CI 0.1 - 0.7), but increased to 4% four years after arrival, showing no improvement from baseline (OR 0.8, 95% CI 0.4 - 2.0). No interactions were observed between changes over time and baseline variables. Conclusions After four years in Norway, Syrian refugees reported improvement in anxiety/depression, but PTSD symptoms worsened. This highlights the need for ongoing support that extends beyond the initial phases of resettlement. Key messages • Refugees face various risk factors that affect their mental health throughout the migration process. • Ongoing mental health support for refugees is essential, beyond the initial resettlement phase.