Mafātīḥal-ʿUlūm by al-Khwārizmī is oneofthe most importantencyclopedicworks ofthefourth century AH. Inadditiontointroducingvarious sciencesandtheir common terminologies, it provides valuable information on the financial and administrative(dīwān) system of its time. Despite the significance of this work for understanding the administrative and financial structure of Islamic civilization, the role of its financial terms and concepts in explaining the process of the formation of financial knowledge (accounting) in Islam has received limited independent scholarly attention. Accordingly, the present study seeks to answer the following question: To what extent and in what dimensions did al-Khwārizmī explain financial concepts and terminology inMafātīḥal-ʿUlūm in the process of the formation of financial knowledge? Employing the historical analysis method with a descriptive–analytical approach, this study examines and analyzes the financial concepts and terminology presented in Mafātīḥal-Ulūm.The findings indicate that al-Khwārizmī organized financial topics into three stages. The first stage explains the general and jurisprudential foundations of financial affairs by discussingzakāt,financialniṣāb thresholds, various types of transactions, and their related terminology. The second stage is devoted to introducing specialized financial recording scripts, accounting registers, and the procedures for recording and maintaining accounts. The third stage presents a coherent picture of the financial and administrative system of its time by explaining financial accounting methods, specialized dīwānterminology,and accounting procedures. This organization demonstrates that, beyond its terminological value, Mafātīḥal-ʿUlūmoccupies a significant place in understanding the foundations and development of Islamic financial knowledge and accounting in the fourth century AH.