Although previous research has suggested that parenting style affects children’s peer relationships, the influential mechanism remains a subject of debate. We propose that parental mentalizing plays a crucial role in parenting style and peer relationships. Therefore, this study aimed to explore the relationships between family parenting styles, parental mentalizing, and peer relationships during early adolescence. In this study, 379 primary school students (Mean age = 12.17 years, SD = 0.92) and their parents were assessed using the Family Parenting Style Scale, Peer Relationship Satisfaction Scale, and a distorted mentalizing task. The results showed a mediating effect of parental mentalizing between parenting style and peer relationships. For fathers, a favorable parenting style affects children’s peer relationships through mentalizing. Among mothers, interference, protection, and punishment affect their children’s peer relationships through mentalizing. In conclusion, parenting style affects peer relationships through parental mentalizing. Fathers’/mothers’ parenting style and parental mentalizing affect their children’s peer relationships differently.