The proliferation of digital technologies has transformed retail from a channel-centric model into an integrated ecosystem in which consumers move fluidly between online and physical touchpoints. This review article synthesizes the growing body of literature on omnichannel retailing and its impact on revenue performance. Drawing on 55 scholarly sources spanning the resource-based view, service-dominant logic, and customer journey theory, the article maps the current state of knowledge across three integration dimensions: digital-physical integration, data and analytics integration, and organizational integration. The review identifies distinct revenue mechanisms through which omnichannel strategies operate, including customer acquisition expansion, basket size and cross-selling enhancement, and customer retention and lifetime value improvement. Five research propositions are advanced within a conceptual framework that links integration depth to revenue outcomes, moderated by product category, firm capabilities, and market context. The article concludes with managerial implications for retailers seeking to optimize cross-channel investments and a research agenda addressing longitudinal dynamics, emerging technologies, and measurement standardization.