Objectives <p>The mirror exercise, an intervention instructing women to mindfully self-observe their vulva, has been shown to improve sexual functioning in clinical populations when couched within larger interventions. The current study examined the efficacy of this exercise&#xa0;<i>in isolation</i> in a non-clinical population (college students), as well as the role of mindfulness in predicting intervention benefits.</p> Method <p>Participants (<i>n</i> = 415; after exclusion criteria) were undergraduates who self-reported having a vulva. They were randomly assigned to the vulva mirror exercise or a control condition (foot exercise), then divided by whether mindfulness instructions were present vs. absent (four&#xa0;total conditions: two exercise types x two mindfulness instructions). Before and after the intervention, participants completed online questionnaires measuring vulva self-image (VSI) and state mindfulness, the latter consisting of retrospective reports about mindfulness experienced during the exercise.</p> Results <p>Participants in the vulva condition showed larger improvements in vulva self-image than participants in the foot condition (<i>β</i> = 0.06, <i>p</i> = 0.025), and significant increases in VSI pre- vs. post-intervention (<i>d</i> = 0.25, <i>p</i> &lt; 0.001). Although there was not a significant effect of mindfulness instructions on vulva self-image at the group level, at the individual level, participants who reported being more mindful during the exercise showed larger benefits from the vulva mirror intervention (<i>β</i> = 0.11, <i>p</i> = 0.003).</p> Conclusions <p>Our findings provide preliminary efficacy of the vulva mirror exercise on improving vulva self-image among healthy young adults and highlight the importance of cultivating a mindful, non-reactive stance while engaging in this exercise.</p> Preregistration <p>The study design, hypotheses, and analyses were preregistered on the Open Science Framework (OSF): <a href="https://osf.io/f948t/">https://osf.io/f948t/</a>.</p>