The purpose of this study is to identify the latent profiles of Chinese adolescents' family (parent-adolescent and sibling) relationships prior to and during the COVID-19 pandemic, as well as associations between those profiles and adolescents' emotional and behavioral responses. A total of 2,305 adolescents from China aged between 10 and 18 years completed measures of parent-adolescent relationships, sibling relationships, and emotional and behavioral responses during the pandemic. Four profiles of family relationships were identified via latent profile analysis and categorized as Cohesive-Decline, Mild-Decline, Conflictual-Stable, and Indifferent-Stable. Adolescents with a Conflictual-Stable profile reported more emotional and behavioral responses compared to the other profiles. In contrast, adolescents with a Cohesive-Decline profile exhibited fewer emotional responses compared to the other profiles. Adolescents with a Mild-Decline profile had fewer emotional responses than those with an Indifferent-Stable profile. These results shed light on the patterns and consequences of family relationships during the COVID-19 pandemic and have substantial implications for interventions involving family relationships in the context of regular epidemic prevention and control.