<p>Both problematic Internet use (PIU) and bullying perpetration are problem behaviors among adolescents, which exert an adverse influence on their psychosocial well-being. Although the problem behavior theory suggests an association between PIU and bullying perpetration, empirical studies investigating this link are limited. Additionally, little is known about the factors that moderate the strength of this association. This study used a multi-informant approach to investigate PIU’s associations with traditional and cyberbullying perpetration among Chinese adolescents and the moderating effects of students’ perceived school climate and gender on this association. A total of 751 students (<i>Mean</i>_age = 12.89, 359 boys and 392 girls) in 7th and 8th grades from three middle schools in Chengdu, China completed measures of traditional bullying perpetration, cyberbullying perpetration, and perceived school climate. Their parents or guardians completed ratings on adolescents’ PIU. Results indicated that PIU was positively associated with traditional bullying and cyberbullying perpetration. Moreover, the risk association between PIU and traditional bullying perpetration was attenuated among adolescents who perceived a more positive school climate than those who perceived a less positive school climate. The risk association between PIU and traditional bullying perpetration was stronger among boys than girls. Findings highlight the importance of implementing school-wide and gender-sensitive prevention efforts to reduce bullying perpetration and address the negative impact of PIU.</p>