ObjectivesGrowing evidence suggests that mindfulness-based programmes (MBPs) can reduce stress and burnout among social workers. How MBPs support changes in these outcomes is unclear. This study attempts to identify what some of these mechanisms might be, using the clinically modified Buddhist psychological model (CBPM) as a guiding framework.MethodThis study used data from two randomised controlled trials investigating the impact of MBP participation on social worker stress and burnout. The data from participants (n = 94) who completed a Mindfulness-based Social Work and Self-Care (MBSWSC) programme, or a mindfulness and self-compassion programme (MSC) were combined. Structural equation models were constructed, and conditional direct and indirect effect models of changes in the CBPM domains (mindfulness, self-compassion, attention regulation, acceptance, non-attachment, non-aversion), mediating variables (rumination and worry) and outcomes (stress and burnout) were tested.ResultsThe results suggest that CBPM models, through mediated effects on stress, depersonalisation, and personal accomplishment, as well as direct and mediated effects on stress, emotional exhaustion, and depersonalisation, can provide useful frameworks for explaining how MBPs reduce stress and burnout among social workers. This study also found several other significant conditional direct and indirect effects. The pattern of these relationships indicate that multiple outcomes could be improved through different CBPM domains.ConclusionThis study provides initial evidence on the potential mechanisms through which MBP participation acts to reduce stress and burnout in social workers.Preregistrationhttps://www.clinicaltrials.gov; Unique identifier: NCT05519267 and NCT05538650.