Research has indicated that mindfulness is a protective factor against suicidal ideation. However, the dynamic reciprocal relation between them has been understudied. In this study, 110 female college students with suicidal ideation completed a measure of trait mindfulness and a 28-day diary of suicidal ideation and three-dimensional state mindfulness, including acting with awareness, present-moment attention, and nonjudgmental acceptance. Dynamic structural equation modeling was used to examine the dynamic and bidirectional effects between dimensions of state mindfulness and suicidal ideation and the moderating effect of trait mindfulness. Results showed that suicidal ideation predicted lower levels of present-moment attention the next day. More importantly, there was a dynamic and bidirectional relation between nonjudgmental acceptance and suicidal ideation for people with trait mindfulness higher than the average level (i.e.,