Purpose: This research aims to investigate the effect of company’s Informational Environment Characteristics (IEC) (investors' sophistication, financial analysts’ coverage, and audit quality) on the direct relationship between mandatory adoption of International Financial Reporting Standards (IFRS) and both of relevance and faithful representation of accounting information. In addition to examining the conditionality of the mediating role of comparability with (IEC) as a moderating variables, in explaining the indirect relationship between the adoption of (IFRS) and both of relevance and faithful representation of accounting information. Design/methodology: This research depends on archival data methodology using historical data, such as: companys' stock prices, returns, and financial reports. In addition to, use path analysis methodology and building structural models for examining Moderated-Mediation relations by running Stata (V.17) using a purposive sample of (96) companies from non-financial companies listed and traded on the Egyptian Stock Exchange, during the period from 2011 to 2019. Results: In periods after the adoption of IFRS, the results indicate that, a decrease in relevance of the book value of shareholders’ equity measured by (BV). While, both of relevance of earnings measured by (EPS) and faithful representation of earnings measured by (AQ; IS) increased. Also, results showed a moderating effect of companies’ (IEC) on direct (indirect) relationship between adoption of IFRS and both of relevance and faithful representation of accounting information (through mediating comparability). According to robustness using alternative measures of some research variables, there exist variations in company’s (IEC), and moderator values effects on paths of direct (indirect) relationship between adoption of IFRS and both of relevance and faithful representation of accounting information (through mediating comparability). Originality / Value: For the best knowledge of the researcher, the current paper is one of the first researches in the Egyptian business environment, which focuses on presenting empirical evidence, about the role of mandatory adoption of IFRS in maximizing relevance and faithful representation of accounting information directly as well as validating claims about the role of IFRS in enhancing comparability, in order to enhance the relevance of accounting information but not at the expense of reducing its faithful representation. In addition to determining role of company’s (IEC) in moderating paths of direct (indirect) relationship between adoption of IFRS and both of relevance and faithful representation of accounting information (through mediating comparability).