This study examined the effect of Citizenship Behaviour on Business Sustainability of Small and Medium Enterprises SMEs in Abuja, with Dynamic Capability as a moderating variable. The study focused on four dimensions of business sustainability: financial, environmental, social, and human sustainability. A survey research design was adopted, and data were collected through structured questionnaires administered to SME owners, managers, and employees in Abuja. Out of 300 copies of the questionnaire distributed, 175 valid responses were retrieved and used for analysis. Descriptive statistics and regression analysis were employed to analyze the data and test the hypotheses. The findings revealed that Citizenship Behaviour has a positive and significant effect on the financial dimension of business sustainability. The study also found that Citizenship Behaviour significantly affects the environmental, social, and human dimensions of business sustainability among SMEs in Abuja. These findings suggest that voluntary employee support, cooperation, commitment, responsible resource use, and extra-role behaviour contribute meaningfully to the sustainability of SMEs. Furthermore, the study found that Dynamic Capability partially moderates the relationship between Citizenship Behaviour and Business Sustainability. Specifically, Dynamic Capability significantly moderated the financial, environmental, and social dimensions, but its moderating effect on the human dimension was not significant at the 5% level. The study concluded that Citizenship Behaviour is an important driver of business sustainability among SMEs in Abuja, while Dynamic Capability plays a partial moderating role. The study recommended that SME owners and managers should encourage citizenship behaviour, strengthen adaptive capabilities, promote employee involvement, and support sustainable business practices.