Students in health professions often face high levels of stress due to demanding academic schedules, heavy workloads, disrupted work–life balance, and sleep deprivation. Addressing stress during their education can prevent negative consequences for their mental health and the well-being of their future patients. Previous reviews on the effectiveness of mindfulness-based interventions (MBIs) focused on working health professionals or included a wide range of intervention types and durations. This study aims to investigate the effect of 6- to 12-week MBIs with 1- to 2-h weekly sessions on stress in future health professionals. We conducted a systematic review and meta-analysis of randomized controlled trials published in English by searching Embase, Medline, Web of Science, Cochrane Central Register of Controlled Trials, and PsycINFO. We used post-intervention stress levels and standard deviations to assess the ability of MBIs to reduce stress, summarized by the standardized mean difference (SMD). This review is reported according to the PRISMA checklist (2020). We identified 2932 studies, of which 11 were included in the systematic review and 10 had sufficient data for inclusion in the meta-analysis. The overall effect of MBIs on reducing stress was a SMD of 0.60 (95% CI [0.27, 0.94]). Our study provides evidence that MBIs have a moderate reducing effect on stress in students in health professions; however, given the high risk of bias, these findings should be interpreted with caution, and further high-quality studies are needed.