Objectives <p>Online mindfulness practices can alleviate adolescents’ negative emotions but often face low engagement and adherence. Chinese pastoral poetry, emphasizing harmony between humans and nature, resonates culturally with Chinese adolescents and evokes a meditative sense of tranquility. This study integrated Chinese pastoral poetry into online mindfulness practice and incorporated guided practice support to enhance adherence and improve intervention effectiveness among distressed adolescents.</p> Method <p>A randomized controlled study (<i>n</i> = 142, aged 16–18) compared a 6-week online poetry-integrated mindfulness intervention (experimental) to a standard online mindfulness intervention (control). Negative emotions and well-being were assessed through diaries and self-reports. Feasibility of the interventions, including adherence, was also evaluated.</p> Results <p>Both groups showed significant reductions in negative emotions, but the experimental group demonstrated a greater decrease (frequency: mean difference = -2.57, 95% CI: -3.46 to -1.68,<i> p</i> &lt; 0.001; intensity: mean difference = -0.96, 95% CI: -1.17 to -0.75, <i>p</i> &lt; 0.001), with effects sustained at the 3-month follow-up. The experimental group also reported higher intervention acceptability (mean difference = 1.48, 95% CI: 0.15 to 2.81, <i>p</i> = 0.02) and a greater completion rate (93% vs. 79% in the control group).</p> Conclusions <p>Online mindfulness integrated with pastoral poetry was more effective than standard online mindfulness practice in enhancing adolescents’ emotional well-being and adherence. The incorporation of guided practice support also contributed to increased engagement and adherence. This culturally adapted approach showed potential for optimizing mental health interventions for distressed adolescents.</p> Preregistration <p>&#xa0;This study was not preregistered.</p>