The study highlighted the persisting global health crisis of HIV/AIDS and the recent disruptions caused by economic and humanitarian crises along with the COVID-19 pandemic. These factors have troubled the established HIV/AIDS diagnosis and treatment services which are critical steps for preventing the disease. Thus, this study aims to address this challenge and improve the quality-of-service delivery by developing a knowledge-based system which integrates an intelligent counseling and medical data storage and access functionalities with the testing and treatment services of HIV/AIDS. The task of diagnosis and treatment of HIV/AIDS involves several determinant rules that govern the decision-making process. These rules play a crucial role in identifying and suggesting appropriate treatments. Thus, a rule-based reasoning technique is used to address the problem due to its explicit definition of facts, rules, relationships, actions, and suggestions. It offers a structured framework for decision-making, where predefined rules assist users by providing relevant information and the logical reasoning process for identifying HIV status and recommending appropriate treatments. By using these rules, the model consistently generates the same results for identical scenarios, ensuring reliability in the diagnosis and treatment of HIV/AIDS. The study followed a qualitative research approach and data collection methods such as semi structured interviews, and documentation. The required knowledge is acquired from medical experts involved in HIV/AIDS diagnosis and treatment services in the Debre Tabor referral hospital. In addition, governmental strategic documents, guidelines, manuals, and related journals are used as secondary sources of data selected by purposive sampling technique. A content analysis method is used to explore the knowledge, experiences, skills, and processes related to counseling, testing, and treatment services. Graphical decision tree and forward chaining reasoning techniques are used to model and represent the knowledge respectively. Angular web framework with typescript programming language is used for the implementation. The findings highlighted the effectiveness of the KBS model in providing counseling, testing, and treatment services. The counseling service offered information and support to individuals undergoing HIV testing, helping them make informed decisions. The testing service accurately analyzed samples of blood test results, aiding in early detection and treatment. The treatment recommendation service suggested antiretroviral therapy regimen types. XI Furthermore, the proposed model included medical data storage and access services with the KBS model for retrieval and utilization of diagnosis and treatment-related information. This service contributes to resource management and promotes collaboration in HIV/AIDS diagnosis and treatment tasks. In conclusion, this study presented a promising knowledge-based system model for the management of HIV/AIDS by integrating intelligent counseling services and data storage and accessing capabilities. Thus, it makes a significant contribution to the ongoing fight against the disease. Keywords: Intelligent counseling, HIV/AIDS testing, HIV/AIDS treatment