Introduction Career indecision is a prevalent developmental challenge among emerging adults, yet the mechanisms through which peer influence relates to decisional difficulty remain poorly understood. Drawing on Social Cognitive Career Theory (SCCT) and the career calling literature, this study tested a moderated mediation model in which positive peer career support and negative peer career pressure are linked to career indecision through career calling, with internalized prosocial values moderating the association between negative peer pressure and calling. Methods Survey data from 524 undergraduates at a comprehensive Chinese university were analyzed using confirmatory factor analysis, latent moderated structural equations (LMS), and bias-corrected bootstrap procedures. Results Positive peer career support was positively associated with career calling (β = 0.31, p < 0.001), whereas negative peer career pressure was negatively associated with career calling (β = 0.27, p < 0.001); only negative peer pressure showed a direct association with career indecision. Career calling was negatively associated with career indecision (β = 0.46, p < 0.001) and fully mediated the link between positive peer support and career indecision, while partially mediating the link between negative peer pressure and career indecision. Internalized prosocial values moderated the association between negative peer pressure and career calling (interaction β = 0.18, p < 0.001); the conditional indirect association of negative peer pressure was substantially attenuated at high levels of value internalization. Discussion These findings extend SCCT by showing that internalized prosocial values may serve as a contextual protective factor that attenuates the maladaptive association of peer pressure with meaning-based career development, and highlight the importance of distinguishing supportive from pressuring peer dynamics in understanding career decision-making among emerging adults in a collectivist cultural context. Given the cross-sectional design, longitudinal replication is needed to corroborate the proposed directional relationships.