Objectives: Previous research has established the protective role of mindfulness against various psychological disorders and maladaptive behaviours. However, the associations between specific facets of mindfulness and diverse mental health and behavioural outcomes have not been thoroughly investigated in populations with risky occupations. The aim of this study was to examine the direct and indirect associations between the five facets of mindfulness and prevalent mental health and behavioural outcomes among firefighters, including depression, post-traumatic stress disorder (PTSD), anger, suicide risk, sleep quality, and alcohol use. Method: The assessment scores of 685 career firefighters (Mage = 38.40, SD = 8.64; 93.6% males; 77.7% White) including 154 (22.5%) military veterans, who completed measures of mindfulness, depression, PTSD, anger, suicide risk, sleep quality, and alcohol use, were investigated using both directional and non-directional network analysis. Results: Directional network analysis indicated the primary role of anger in triggering PTSD and impacting mindfulness, leading to alcohol use, suicidal ideation, impaired sleep quality, and depression as an outcome. Mindfulness facets of Non-reactivity, Non-judging, and Describing were negatively associated with depression, while the Acting with awareness facet was inversely linked to anger. Conclusion: This study emphasizes the clinical significance of targeting specific mindfulness facets in interventions for high-risk occupations, such as firefighters. Focusing on Non-reactivity, Non-judging, Describing, and Acting with awareness may help mitigate anger, depression, and other negative outcomes. Addressing anger management could be especially important in preventing or reducing PTSD, alcohol use, suicidal ideation, sleep disturbances, and depression, ultimately enhancing psychological well-being and quality of life.