Objectives <p>Positive emotions are important mediators of loving-kindness and compassion meditation (LKCM) interventions for mental health. However, the neural mechanisms underlying LKCM remain elusive, and little is known about the association between positive emotions and brain activity during LKCM. The present study investigated the effects of an LKCM intervention on electroencephalography (EEG) findings and examined the associations between EEG findings and positive emotions during the LKCM intervention.</p> Method <p>Fifty-one female college students were randomly assigned to either the LKCM group or the waitlist group. Self-reported positive emotions and EEG findings during LKCM practice were measured before and after the intervention.</p> Results <p>A single session of LKCM induced greater emotional arousal (<i>d</i> = 0.49) and frontal midline theta (<i>d</i> = 0.75) but elicited lower levels of low-arousal positive emotions (<i>d</i> = − 0.40) and lateral frontoparietal gamma (<i>d</i>-values &lt; − 0.39) than baseline rest. The effects of a single session of LKCM on prosocial positive emotions and emotional valence were moderated by task order. Left lateral frontal gamma activity was positively associated with emotional valence (<i>ρ</i> = 0.63). Compared with the waitlist group, the intervention group exhibited greater levels of frontal midline theta during LKCM after intervention (<i>d</i> = 0.67).</p> Conclusions <p>The present study highlights the important role of left lateral frontal gamma activity in the process of LKCM generating positive emotions. LKCM intervention may facilitate frontal midline theta activity. Future studies should further examine the effect of practice order and duration on emotional outcomes.</p> Preregistration <p>This study was preregistered at OSF (<a href="https://osf.io/se8jg">https://osf.io/se8jg</a>).</p>