When online vendors have gained a strong user base through a flagship product, the basic principles of competitive strategy dictate that they seek to extend their product lines. Taking advantage of existing traffic to introduce a new product presents a critical opportunity for these vendors. Since users increasingly emphasize cross-product integration, the integration of newly extended products with a flagship product is important in exploiting the user base. In contrast to the proliferation of cross-product integration worldwide, little is known about relationships between product integration and cognitive, behavioral, and decision measures of users. Drawing on the literature in learning efficacy and value transference, we assessed and compared the effects of three product integration formats currently used online (value-added integration, add-on module integration, and data-interface integration) on consumers’ intention to use an extended product in a scenario-based experiment. The findings suggest that value-added integration is associated with higher levels of perceived diagnosticity and perceived entitativity than data-interface and add-on module integration. Perceived diagnosticity and perceived entitativity, in turn, have a significant effect on consumers’ intention to use the extended product. This study contributes to both research and practice by advancing the overall understanding of how to exploit the online user base, as well as by providing important insights into online product design and promotion.