<p>Emerging adulthood is a critical developmental period marked by heightened emotional volatility and increased vulnerability to anxiety and depression, yet the mechanisms linking emotion regulation habits to emotional distress remain unclear. Traditional approaches often examine emotions in isolation, overlooking how negative emotions unfold as dynamic networks that may sustain distress over time. Guided by a dynamic network perspective, this study examined whether negative emotion network density, further decomposed into emotional inertia and interconnectedness, mediated the associations between emotion regulation strategies and subsequent emotional distress. Chinese undergraduates (<i>N</i> = 421; <i>M</i>_age = 19.16 years, <i>SD</i> = 1.04 years; 73.4% female) completed a 14-day diary assessing negative emotions, with depressive and anxiety symptoms measured at baseline and reassessed at 2-week and 6-month follow-ups. Mediation analyses showed that lower habitual use of cognitive reappraisal predicted higher emotional distress at the 2-week, but not the 6-month, follow-up via increased negative emotion network density. This indirect effect was primarily driven by emotional interconnectedness rather than emotional inertia. Notably, emotional interconnectedness remained prospectively associated with depressive symptoms over the longer term. In contrast, expressive suppression showed no indirect associations with emotional distress through network density or its componets. These findings highlight emotion network density, particularly interconnectedness, as a dynamic emotional mechanism through which lower habitual use of reappraisal contributes to emotional distress during emerging adulthood.</p>