The proposed two-arm randomized waitlist-controlled trial will use a mixed-methods design to investigate the effects of dyadic mindfulness on physio-psycho-spiritual outcomes in people with Parkinson's Disease (PwPD) and their family caregivers. One hundred Chinese patient-caregiver dyads will be randomized to receive eight weekly 90-minute dyadic mindfulness sessions or usual care. Outcome measures include negative emotions (primary outcome), patient-caregiver relationship, mindfulness, HRQOL, gut microbiome, PD-related symptoms, and caregiving burden. An actor-partner interdependence model will be used to explore the interactions of treatment effects within the dyads. The dyads will be assessed at baseline(T0), post-intervention(T1), and 4-months post-intervention(T2). The investigators will also invite 25 dyads to attend in-depth interviews exploring their experiences, perceived changes, and factors attributable to the effectiveness/ineffectiveness of the intervention. Generalized linear mixed-effects (GLME) with intention-to-treat analysis will be used to compare the changes in outcomes over time within and between the two arms. The findings will be triangulated to provide a comprehensive evaluation of the intervention's effectiveness. This study will generate rigorous scientific evidence to inform the application of dyadic mindfulness as a public health practice preventing the progression of psychological distress in PwPD and caregivers to clinically severe levels. Its self-help nature also enriches the primary care for this clinical cohort.