Many firms use mobile applications and mobile websites to increase their product sales. However, little is known about how to optimize these channels for maximum sales. We obtained secondary data from an e-commerce company in China and compared the effectiveness of mobile applications and mobile websites in driving direct and indirect sales. Using the seemingly unrelated regression method, we found that mobile applications are more effective at increasing indirect sales compared to mobile websites but do not have the same positive impact on direct sales. The negative impact of mobile applications on direct sales is mitigated when non-monetary promotions, such as free gifts, are associated with the product. In contrast, the positive impact of mobile applications on indirect sales is enhanced when the product includes monetary promotions, such as discounts. Our study enriches the research into multi-channel promotion and provides practical guidance for firms.