One of the central questions in the theory of the intergenerational transmission of psychological symptoms is to identify whether parenting practices explain the transmission of psychological symptoms from parents to youth. This study examined the mediating mechanism of mindful parenting in the relationship between parental anxiety and youth’s emotional and behavioral difficulties. In three waves separated by six months, longitudinal data were collected from 692 Spanish youth (54% girls) aged between 9 and 15 years (Mage = 12.84 years, SD = 1.22 years at Wave 1) and their parents. Path analysis showed that maternal mindful parenting mediated the relationship between maternal anxiety and the youth’s emotional and behavioral difficulties. No mediating effect was found concerning fathers; however, marginal bidirectional relationships were obtained between paternal mindful parenting and youth’s emotional and behavioral difficulties. This study addresses one of the main concerns about the theory of intergenerational transmission using a multi-informant and longitudinal study design, concluding that maternal anxiety predicts less mindful parenting practices and these in turn predict youth’s emotional and behavioral difficulties.