Metacognition is important for self-regulated learning and it has recently been argued that it may play an important role in self-control more generally. We studied multiple aspects of metacognition in self-control, namely metacognitive knowledge including a person´s repertoire (“toolbox”) of different self-regulatory strategies, metacognitive regulation (planning, monitoring, and evaluation), and polyregulation (using more self-regulatory strategies in a single self-control conflict) as predictors of people´s self-control success in daily life. In a preregistered experience sampling study, N = 503 participants reported their self-control conflicts up to eight times per day for 10 days, yielding 9,639 reports of daily self-control conflicts. Analyses showed that higher levels of metacognitive knowledge, planning, monitoring, evaluation, and polyregulation as well as a larger strategy repertoire were associated with higher levels of success in resolving daily self-control conflicts. Additionally, higher levels of trait self-control were associated with higher levels of metacognitive knowledge, planning, and monitoring. These findings highlight the importance of metacognition and polyregulation for successful self-control.