Objective <p>Mindfulness-based interventions (MBIs) have been shown to alleviate emotional distress in the early stage, yet the mechanisms of action are not well understood. The present study aimed to explore the mechanisms of MBIs at early stage using network analysis.</p> Method <p>The study utilized data from three randomized controlled trials involving 1,084 adults experiencing high emotional distress. Participants were assigned to either a Mindfulness Intervention for Emotional Distress (MIED) group (<i>n</i> = 530) or a waitlist control group (<i>n</i> = 554). Psychological variables, including mindfulness, anxiety, depression, and general emotional distress, were measured weekly. Cross-lagged panel network analyses were employed to examine the interactions and changes in these variables during the first 3&#xa0;weeks.</p> Results <p>MIED changed emotional distress and all five facets of mindfulness as early as the first week. Nonjudging and acting with awareness showed a reciprocal relationship with general emotional distress during the early stage. Nonreactivity showed reciprocal a relationship with anxiety and depression in the second week. Additionally, higher levels of observing and describing predicted lower levels of emotional distress in the following week.</p> Conclusion <p>These findings highlight the early and dynamic effects of MIED on both emotional distress and mindfulness. Different facets of mindfulness contribute uniquely to distress reduction and should be cultivated during the early stages of intervention to enhance the overall therapeutic benefits of MBIs.</p> Preregistration <p>Three trials were preregistered in the Chinese Clinical Trial Registry (<a href="http://www.chictr.org.cn/">http://www.chictr.org.cn/</a>). The analysis plan of present study was preregistered on Open Science Frame Registries (<a href="https://osf.io/registries">https://osf.io/registries</a>).</p>