Small businesses in Nigeria confront a significant challenge in accessing necessary funds, hindering their potential for growth and development. Recognizing this hurdle, the financing of small businesses by Microfinance Banks has emerged as a pivotal component of the government's economic policies. These institutions focus on deposit mobilization within their areas of operation, extending microcredits or overdrafts to customers who lack access to conventional banking services.Small Business Growth is the dependent variable, while microfinance deposits, microfinance institution size, and microfinance loans constitute the independent variables. Utilizing monthly secondary time series data from the Central Bank of Nigeria’s Statistical Bulletin spanning from 2006 - 2021, the study employed the Autoregressive Distributed Lags (ARDL) Technique. The Unit Root test indicated the suitability of employing the ARDL estimation technique given the stationarity nature of the variables.Findings revealed a significant but negative impact of microfinance banks on the short-term expansion of small businesses, yet a positive and noticeable effect over the long term. Furthermore, the study indicated that the size of microfinance institutions holds minimal influence on the long-term success of small businesses. Interestingly, microfinance loans exhibited a negative and significant effect on short-term growth but demonstrated a positive and significant impact in the long term.Based on the outcomes, policymakers and microfinance institutions should focus on effective deposit mobilization and establish sustainable long-term financing models for small businesses. Prioritizing microfinance service quality over institution size is advised. Government policies should encourage high-quality financial services, emphasizing timely and affordable credit, savings, insurance, and other relevant products. Finally, fostering responsible lending practices is crucial, requiring robust screening, monitoring mechanisms, suitable interest rates, repayment terms, and financial education for borrowers to ensure effective utilization of loans without burdening small businesses.