In Portugal, like in other European countries, the COVID-19 pandemic aggravated the risk of poverty and social exclusion faced by migrants. This study aimed to assess mental health and well-being, and their social determinants, among Brazilian and Cape Verdean immigrant populations two years after the COVID-19 pandemic while exploring the role of positive psychological factors such as resilience and perceived social support. We conducted a cross-sectional survey combining online and face-to-face questionnaires for data collection between February and November 2022 on dimensions of mental health considered potentially relevant to the post-pandemic context: psychological distress, anxiety, and depression. Overall, 604 immigrants were included (322 Brazilian and 282 Cape Verdean); 58.5% of those surveyed were women and 41.5% were men. The results revealed that gender (being a woman) was associated with both psychological distress and depression, higher education was associated with anxiety, and that, for the three mental health dimensions under analysis, the perception of discrimination and resilience were negative and positive predictors, respectively. Findings can inform the design and implementation of relevant public mental health promotion programs with a focus on equity targeted to the general population. Such programs would help to address the psychological and social impacts of this long-term, insidious global pandemic that has challenged governments, health care systems, health care professionals, individuals, families, and communities worldwide.