Digital transformation, the diffusion of digital platforms, and post-COVID-19 shifts in demand are reshaping the competitive structure of the foodservice industry. Amid these changes, small foodservice businesses are diversifying their sales channels to enhance market access and stabilize revenue. However, prior research on diversification has largely focused on product and business diversification in large firms and manufacturing contexts. Grounded in the resource-based view, this study uses data from the 2024 Survey on the Management Status of the Restaurant Business to examine the effect of sales channel diversification on business performance. It further tests the moderating effects of organizational change capability, digitalization, and competitive intensity. Sales channel diversification is measured by the number of sales channels and the balance of sales among channels. The findings reveal that sales channel diversification is positively associated with business performance, with this effect strengthened by higher levels of organizational change capability and digitalization, whereas competitive intensity does not significantly moderate the relationship. This study reinterprets sales channel diversification as a channel portfolio strategy for these businesses, extending the diversification literature and identifying how internal capabilities and digital infrastructure shape the performance of multichannel operations.