This paper seeks to investigate the factors that impact the adoption of E-commerce by small and medium-sized enterprises (SMEs) in Sri Lanka. Explores the impact of various determinants, including performance expectancy, effort expectancy, social influence, facilitating conditions, perceived risk, and adoption intention on the adoption of e-commerce in Sri Lankan SMEs. The study is based on SMEs in the country. The study encompasses Small and Medium Enterprises (SMEs) from four provinces across the country, spanning ten different industries. A sample of 252 Small and Medium Enterprises (SMEs) across 10 industrial sectors in 4 regions was selected using a simple random sampling technique.The results indicated that Performance Expectancy, Effort Expectancy, Facilitating Conditions, and Perceived Risk as major influences on the adoption of e-commerce significantly influenced the adoption of e-commerce by SMEs in Sri Lanka. However, it was observed that comparatively reduced influence of Social Influence on E-commerce adoption among SMEs.