Parental work-family conflict undermines family functioning, which in turn may impair children’s peer functioning. Using a longitudinal design spanning across 2 years, the present study examined whether paternal/maternal work-family conflict could predict interparental conflict and, in turn, whether such conflict contributed to adolescent affiliation with deviant peers. Additionally, this study also explored the moderating role of adolescent mindfulness on these relationships. As part of a large longitudinal project, 1427 adolescents (773 boys and 654 girls; aged from 12 to 15 years, M = 12.66 years, SD = 0.63) completed questionnaires regarding perceived interparental conflict, deviant peer affiliation, and mindfulness, and both parents reported on questionnaires regarding their own work-family conflict at three-time points with 1-year intervals. Results indicated that paternal but not maternal work-family conflict positively predicted interparental conflict, which was further positively predictive of deviant peer affiliation for adolescents with low but not high mindfulness. Our study revealed the role of paternal work-family conflict as a seemingly distal but relatively proximal risk factor for adolescents’ affiliation with deviant peers, as well as the buffering role of mindfulness on the longitudinal relations.