Online platforms have emerged as an alternative method for companies to directly introduce and promote their products to their target audience, bypassing the need for third-party endorsements. However, the effectiveness of self-promotion compared to external promotion remains uncertain. This study utilizes role theory and focuses on a specialized online community platform for technological products to examine the impact of external promoters versus internal promoters. Our findings reveal that external promoters are more effective in promoting products, as they receive a higher number of upvotes from platform supporters compared to internal promoters. Additionally, the effectiveness of external promoters is enhanced when they promote a larger quantity of products. Furthermore, the concurrent promotion of additional products influences the effectiveness of a focal product’s promotion in a complex manner, revealing the intricacies of promotional practices in the dynamic context of new product introductions. Overall, our research underscores the significance of individuals maintaining their primary roles to avoid role conflict and enhance effectiveness.