Mobile payment technology (MPT) has emerged as a tool with the potential to advance financial inclusion and sustainable development. However, the existing literature inadequately explains how sustainability factors influence user behavior toward MPT adoption and how this behavior translates into financial inclusion especially under the influence of mobile transaction tax policies in African countries. This study addresses this gap by examining the antecedents of sustainable usage behaviors of MPT and their implications for digital financial inclusion in Ghana. Specifically, it integrates the triple bottom line (TBL) dimensions (economic, social, and environmental impact) with constructs from the theory of planned behavior (TPB) (attitude, perceived behavioral control, and subjective norms) into a unified sustainability-TPB framework. This study further investigates the moderating role of a mobile transaction tax policy (MTTP) on the relationship between sustainable usage behaviors and financial inclusion. The PLS-SEM method was utilized to analyze the theoretical model using the cross-sectional data of 320 respondents. The findings of this study supported that all TBL dimensions and TPB constructs influence behavioral intention and adoption through the usage of mobile payment technology and consequently financial inclusion. Notably, the mobile transaction tax policy negatively impacts the adoption of sustainable behaviors and financial inclusion. This study contributes to the current theoretical discourse on sustainable consumer behaviors and positions it on the broader sustainable development framework through financial inclusion by providing a shred of empirical evidence in the Ghanaian mobile payment industry perspective. The practical and policy implications are also suggested.