This article examines the crucial role of behavioral beliefs, particularly perceived fluency, in the adoption and utilization of omnichannel services. This study draws on the Technology Acceptance Model (TAM), the 3Q Model, and user satisfaction theory to develop a model linking channel integration quality to behavioral beliefs. It examines how quality dimensions affect perceived fluency and service usage. A survey of 281 omnichannel service users in Vietnam was conducted using convenience sampling. The data were analyzed with Structural Equation Modeling (SEM). The empirical findings confirm that channel service transparency, channel choice breadth, content consistency, and process consistency all exert a significant positive influence on perceived fluency. Crucially, perceived fluency is found to have a strong positive impact on omnichannel service usage. Theoretically, this research extends established information systems and marketing models by empirically validating their applicability within Vietnam’s dynamic omnichannel environment. Practically, the study underscores the critical importance for businesses to strategically enhance channel integration quality to cultivate a seamless and fluent customer experience, thereby fostering greater omnichannel adoption. The paper also discusses the limitations of the study and outlines promising avenues for future research.