Abstract: The growth of EC-B2B System adoption and capability has become a requirement for effectively servicing the businesses of many large and Small-to-Medium Enterprises (SMEs) around the world. In this current research, perceptions of enterprise managers of four indicators: specifically productivity, profits, sales and costs are used to measure the performance before and after the adoption of EC-B2B Systems. The study explored the perceptions of SMEs’ managers in Jordan regarding the adoption of EC-B2B Systems and its effects on enterprises’ performance improvements. This aim achieved through: identifying the current state of adoption of EC-B2B Systems by selected enterprises in Jordan. Discussing and determining performance concepts and influential factors that relate to EC-B2B System adoption within enterprises (SMEs) in Jordan. It is important for managers to understand how EC-B2B System activities affect the performance of the enterprise. Qualitative and quantitative approaches were used to gain a better understanding of these issues. After screening the data, responses are analyzed using Confirmatory Factor Analysis (CFA) and Structural Equation Modeling (SEM). The main findings of the current study that the EC-B2B Systems have a strong positive correlation with SME’s performance which suggests that the SMEs’ performance improved as the extent of the EC-B2B System adoption increased. This research also concludes that SMEs performance improvements in costs variables are important since enterprises expect to receive technology benefits that exceed costs. In addition, the study concluded that the four performance factors: namely productivity, sales, profitability and costs were the most important contributors and measures of the SMEs’ performance in Jordan.