Nurses make up the single largest healthcare professional group in the Nigerian healthcare system. As frontline healthcare providers, they promote healthy lifestyles to patients and families. However, the determinants of Nigerian nurses’ personal health promoting behaviors (HPBs) remain unknown. Utilizing the socio-ecological model (SEM) approach, this study aimed to explore the perceived facilitators and barriers to Nigerian nurses’ engagement in HPBs. HPBs were operationalized to comprise of healthy dietary behaviors, engagement in physical activity, low-risk alcohol consumption, and non-smoking behaviors. Our study was carried out in a large sub-urban tertiary health facility in Nigeria. Data collection was via face-to-face semi-structured interviews and participants were registered nurses (n = 18). Interview data were transcribed verbatim and analyzed thematically to produce nine themes that were mapped onto corresponding levels of influence on the SEM. Findings show that in Nigeria, nurses perceive there to be a lack of organizational and policy level initiatives and interventions to facilitate their engagement in HPBs. The determinants of Nigerian nurses’ HPBs span across all five levels of the SEM. Nurses perceived more barriers to healthy lifestyle behaviors than facilitators. Engagement in healthy behaviors was heavily influenced by: societal and organizational infrastructure and perceived value for public health; job-related factors such as occupational stress, high workload, lack of protected breaks, and shift-work; cultural and religious beliefs; financial issues; and health-related knowledge. Organizations should provide facilities and services to support healthy lifestyle choices in Nigeria nurses. Government policies should prioritize the promotion of health through the workplace setting, by advocating the development, implementation, regulation, and monitoring of healthy lifestyle policies.