The main purpose of define the relationship between firm performance and corporate transparency. As well, this study determines the relationship between firm performance and competitive advantage. In this study, a sample size of 60 was designated from three sectors (Financial, Industrial, and Service) in Muscat Securities Market (MSM). The secondary data collected is examined with Smart PLS 3.0. The findings of the study have been confirming that high transparency led to increasing the performance of firms. Thus, high transparency enhances performance. The findings revealed that corporate transparency is positively related to competitive advantage, which in turn enhances managerial accounting measurements. Thus, corporate transparency is indeed an important tool for competitive advantage and will enhance firm financial performance. The findings of study found that the majority of companies in Oman has very good disclosed in financial statement transparency and  less disclosure in  social transparency part.