A skilled salesperson can build strong relationships with clients, which fosters loyalty and repeat business. They provide valuable insights into customer preferences and competitive landscapes as well as creating value for their customers, manage customer relationships, and gather information for their firms. Hence, this paper explores how self-efficacy functions as a mediator in the correlation between improvisational behaviour, adaptive selling, and sales performance of salespersons. This study investigates the direct and indirect relationship of self-efficacy with sales performance. This study used a survey research approach using clustered random sampling. Data are collected from 315 salespersons employed by Malaysian commercial banks in Klang Valley via survey questionnaires. Partial Least Squares Structural Equation Modeling (PLS-SEM) was used to analyse the data. The findings indicate that self-efficacy serves as a partial mediator in the relationship between improvisational behaviour and adaptive selling with sales performance. Additionally, the results also showed that improvisational behaviour and adaptive selling are positively related to sales performance. The study concluded that personal factors of salespersons are important in determining their sales performance. Hence, for managers to have a competitive advantage in the banking sector, they need to adopt a more comprehensive understanding of what makes a good customer service provider.