Accounting systems have experienced significant developments, including sophisticated software applications, automation, big data, data analytics, and so on. The purpose of this study is to examine the effect of digitalization of accounting systems on the quality of accounting information and the effectiveness of management decision making in small and medium enterprises (SMEs) in a developing country, Indonesia. Based on the innovation diffusion theory, the hypothesis states that digitalization of the accounting system can improve accuracy and timeliness, cost reduction, and decision making. Data were obtained from questionnaire surveys to SMEs who had implemented the digitalization of the accounting systems. The results showed that the digitalization of the accounting systems had a positive effect on the accuracy and timeliness of accounting information and cost reduction. Furthermore, these two variables had a positive effect on the effectiveness of SME management decision making.