The positive association between meaning in life (MIL) and mindfulness has been supported; however, previous research has been limited to the trait level. To explore the dynamics of mindfulness and MIL in the state level, the present study used the experience sampling method (ESM) and conducted a dynamic structural equation model (DSEM). In addition, we examined the moderation of baseline depression in this dynamic relationship and the protective role of the dynamics on depression. We recruited 184 college students (Mage = 21.58, 33.15% male), who reported three times a day for 14 consecutive days, and analyzed the 7726 collected responses. Firstly, a virtuous cycle between mindfulness and MIL was proven. Besides, the baseline depressive symptoms moderated the predictive of mindfulness on MIL, suggesting state mindfulness gave people with more depressive symptoms more meaningful in daily life. Lastly, the result also demonstrated the positive prediction of mindfulness on MIL and alleviated the worsening of depressive symptoms within 2 weeks. The findings extended the relationship between MIL and mindfulness from trait level to state level, enriching the self‐determination theory, and examined the unique effect of depressive symptoms in the dynamics.