This study aimed at investigating the prevalence and factors associated with depression, anxiety, and stress symptoms among volunteers who volunteered to carry out free health services in Lagos, Nigeria. It was a cross-sectional survey. The secondary objective was to determine whether there were differences between individuals who were experiencing depression, anxiety, or stress and those who were not. One hundred and sixty-three consecutive health workers were invited to take part in the study. Sociodemographic and clinical data were gathered using a semi-structured proforma. Assessments were further done using the Depression, Anxiety, and Stress Scale. According to the DASS-21 scale, 30.3% had various levels of depression, and various levels of anxiety were detected in 47.5% of participants. Similarly, various levels of stress were detected in 29.5% of the participants. There were significant associations between the sub-domains of depression anxiety and stress. High levels of depression, anxiety and stress were detected among the participants. The higher degree was evident, particularly among the single, female participants. The results will serve as supporting evidence for the timely intervention of further planning of preventative mental health services by the supervising ministry for volunteer health workers within the public and private health sectors. This implicates the need for mental health training. Hospital management and medical policymakers should continue to provide various types of therapies to increase the emotional resilience and coping skills of healthcare workers.