Internal marketing is the handling of employees of an organization as internal customers and as organizational products that satisfy the needs and desires of external customers. Previously, the primary concerns of many organizations were external customers only. However, in today’s world, competition among service companies is high and the company is concerned with internal marketing, or marketing to employees of the organization, in addition to external marketing. The main purpose of the study was to assess the determinants of internal marketing practices on employee job satisfaction in ACSI in the Awi administration zone of Fagitalekoma and Banja woreda ACSI branches. The study used an explanatory, quantitative research design and the data collection method was cross-sectional and used a structured questionnaire for primary data collection. The target populations of the study were 166. Of the 117 selected from the total employees in ACSI at Fagitalkoma and Banja woreda, six branches were selected through a simple random sampling method by Yemen’s formula. Statistical Packages for Social Science (SPSS) version 26.0 was used to analyze data using descriptive and inferential statistics. Multiple regression analysis techniques were used to explain the nature and impact of the relationship between employees’ job satisfaction and the (internal communication, training, work environment, reward, and infrastructure) factors that affect it. The Pearson correlation result of the study showed that there is a positive relationship among determinants of internal marketing dimensions. Training has a positive and strong relationship with job satisfaction, and internal communication, reward, and infrastructure have positive and moderately relationships with job satisfaction, while the work environment has weak relationships with job satisfaction. The result of the regression analysis showed that training, reward, and internal communication explain 37.9% of the change in employee job satisfaction and the analysis revealed that there are other elements that influence employee job satisfaction in ACSI. In order to attain the highest degree of employee job satisfaction, the head branch of ACSI and Awi district ACSI should make every effort to focus on reward, training, and internal communication while engaging in internal marketing operations. Future studies also focus on large-scale and longitudinal studies on other internal marketing dimensions with related institutions.