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.