Inhibitory control is considered a core component of self-regulation. Tremendous advances in early childhood have been attributed to brain maturation processes as well as environmental influences, such as parental co-regulation. Parental self-efficacy represents a key correlate of parenting behaviors and is associated with child outcomes. However, research on the interplay of parental co-regulation, parental self-efficacy and child's inhibitory control in early childhood is scarce. In this study we explore to what extent parents' positive (PCR) and negative co-regulation (NCR) and domain-specific (DSSE) and domain-general (DGSE) self-efficacy beliefs assessed at pre-test (T1) predict toddlers' inhibitory control six weeks later (T2). Furthermore, we examine whether NCR mediates the link between DSSE and parent-reported inhibitory control. Results are based on data from 90 parent-child dyads (children's age: 24-35 months). Parents' PCR, NCR, DSSE and DGSE are assessed via questionnaire. Children's inhibitory control is measured via the Inhibition Scale of the Behavior Rating Inventory of Executive Functions (BRIEF-IN) and a Snack Delay task. Multiple regression analyses reveal that parents' NCR and DSSE, but not PCR and DGSE, significantly predict BRIEF-IN at T2 (controlling for covariates). The indirect effect from parents' DSSE on BRIEF-IN via NCR is not confirmed by the data. No associations are observed regarding children's performance in the Snack Delay task. The present study adds new and important evidence that parents' DSSE and NCR independently predict (parent-reported) inhibitory control in toddlerhood. Parenting interventions should thus not only address parenting practices but target parental self-efficacy beliefs as an important factor, too.