This study investigated the impact of post-COVID-19 syndrome on the quality of life, mental health, and functional capacity of individuals from ethnically diverse and socioeconomically vulnerable populations in the Brazilian Amazon. The sample consisted of 25 clinically diagnosed individuals from remote communities, predominantly women (60%) and racially diverse, including mixed-race (56%), Indigenous (32%), Black (8%), and White (4%) participants. Validated instruments were used to assess fatigue, anxiety, depression, quality of life, and physical performance. The findings revealed high rates of moderate to extreme fatigue (88%) and psychological symptoms, with over half of participants showing signs of anxiety or depression. Functional impairment was confirmed through the 1-Minute Sit-to-Stand Test. Correlation analyses showed that older age, lower education, and lower income were associated with worse mental health and quality of life outcomes. Cluster and principal component analyses identified distinct symptomatic and sociodemographic profiles, with the most disadvantaged groups presenting the greatest burden. These results highlight the disproportionate effects of post-COVID-19 syndrome on vulnerable populations and emphasize the need for comprehensive public health interventions that integrate physical, mental, and social care dimensions.