(1) Background: Practising mindfulness has been suggested in several recent media reports to help employees reduce stress in their effort to balance work and life pressures, especially during the pandemic when they have to work from home. During COVID-19, organisations have also struggled to effectively engage, retain and sustain employees when managing their work remotely. It is uncertain whether there is a close link between mindfulness and sustained workforce engagement. Although data were collected prior to COVID-19, this study contributes to adding new knowledge to this line of research by investigating how the flow-on effect of being mindful and psychological flourishing helps create positive effects on workforce engagement. (2) Methods: Path analysis was run to test the hypothesised relationships among key constructs with a sample of 229 participants. Direct and indirect effects were further tested with organisational mindfulness training program. (3) Results: The findings show that positive emotions gained from being mindful and maintaining a high level of psychological flourishing enhance workforce engagement. Organisational mindfulness training programs moderated the mediating effect of psychological flourishing on the relationship between mindfulness and workforce engagement, in which the indirect effect of mindfulness on workforce engagement via psychological flourishing is stronger when employees participated in mindfulness exercises and training programs. (4) Conclusions: Positive emotions attained from being mindful and experiencing psychological flourishing help sustain workforce engagement. (5) Implication: In order to sustain an engaged workforce, organisations need to implement effective mindfulness training programs that help the workforce broaden and build their personal resources via psychological flourishing and positive emotions, especially in times of facing difficult circumstances and managing uncertainty in challenging circumstances.