Objectives <p>Young adulthood is a period of both opportunity and vulnerability, particularly as depressive symptoms may emerge or worsen during this still-maturing biopsychosocial development. Although mindfulness-oriented interventions (MOIs) have shown promise across age groups, their effectiveness in reducing depressive symptoms among non-clinical young adults remains unclear. This systematic review synthesized current evidence on the effectiveness of MOIs in reducing subclinical depressive symptoms in this population.</p> Methods <p>Three databases were searched for studies published between 2018 and 2025 in accordance with PRISMA guidelines. Twenty-four studies met the inclusion criteria.</p> Results <p>The included studies showed a general directional pattern, with two-thirds reporting improvements in mindfulness and/or reductions in subclinical depressive symptoms. The evidence base was characterized by substantial heterogeneity in study design, outcome measures, and intervention implementation, and several studies were based on small university student samples or were rated as having a high risk of bias.</p> Conclusions <p>These findings highlight the need for future research that employs more tailored interventions addressing the unique developmental challenges of non-clinical young adulthood, utilizes rigorous methodologies, and includes more diverse populations to enhance mental health support.</p> Preregistration <p>The review protocol was registered on Open Science Framework (Registration DOI: <a href="https://doi.org/10.17605/OSF.IO/VFHT4">https://doi.org/10.17605/OSF.IO/VFHT4</a>).</p>