<p>This study investigated the interplay between peer support, writing self-concept, and the emotions of pride and anxiety in high school writing contexts. Recognizing the complexities of writing as a cognitive and social task, we explored how supportive peer interactions shape students’ emotional responses. Drawing on Social Cognitive Theory, we hypothesized that peer support is positively related to writing self-concept, which, in turn, relates to students’ feelings of pride and anxiety. Data collected from 1408 high school students across various regions in China were analyzed using structural equation modeling. Our findings revealed that peer support was positively associated with pride in writing but not with anxiety. Additionally, writing self-concept partially mediated the relationship between peer support and pride. However, it did not mediate the relationship between peer support and anxiety, highlighting distinct mechanisms for positive and negative emotional outcomes. This research underscores the importance of fostering supportive peer environments to enhance writing self-concept and pride, while suggesting targeted strategies to address writing anxiety. By integrating socio-cognitive dimensions, educators can create emotionally supportive writing instruction that promotes both academic success and emotional well-being.</p>