Objectives Parental stress has been associated with adverse child outcomes and maternal functioning. Yet, maternal factors during pregnancy that can potentially protect against later parental stress, such as mindfulness, have not been studied. Therefore, we aimed to address the possible associations between prenatal mindfulness and levels of parental stress in mothers raising toddlers. Methods Women in the current study (n = 165) were prospectively followed from pregnancy until 3 years after childbirth, as part of a longitudinal population based cohort (HAPPY study). At 22 weeks of pregnancy, women completed the Three Facet Mindfulness Questionnaire-Short Form (TFMQ-SF) to assess facets of mindfulness (acting with awareness, non-judging, and non-reacting). Women completed the Parenting Stress Questionnaire (PSQ) 3 years after childbirth, reporting on three components of parental stress: (1) parent-child relationship problems, (2) parenting problems, and (3) role restriction. Results Results of multiple linear regression analyses showed that the acting with awareness facet of mindfulness during pregnancy was a significant predictor of fewer parent-child relationship problems and parenting problems, even when adjusted for prenatal and maternal distress and child behavior problems. Higher levels of non-reacting during pregnancy were also significantly associated with fewer parenting problems in mothers raising toddlers. Conclusions The current study emphasizes that mindfulness during pregnancy may be a protective factor for later parental stress. More research is needed to confirm these findings and to evaluate the possible benefit of a mindfulness intervention training during pregnancy on parenting and child outcomes.