This study assessed the influence of FinTech-led market outreach on the growth of small and medium enterprises (SMEs) in Kitui County, Kenya, using the number of employees as the indicator of SME growth. Specifically, the study investigated the effects of FinTech-led market access, customer satisfaction, and customer base expansion. A correlational research design was adopted, targeting 4,732 registered SMEs, from which 369 were selected using stratified random sampling. Data were collected from 344 SME owners and managers using structured questionnaires and analysed using descriptive statistics, Pearson correlation, and multiple regression analysis. The findings revealed that FinTech-led market access (β = 0.434, p < 0.001), customer base expansion (β = 0.421, p < 0.001), and customer satisfaction (β = 0.400, p < 0.001) all had significant positive effects on SME growth, with market access emerging as the strongest predictor. The study concludes that strengthening FinTech-enabled market outreach enhances SME expansion and employment creation. It recommends promoting affordable digital financial services, digital infrastructure, and financial literacy to improve SME competitiveness and sustainable economic development.