This study examined the post -implementation impact of IFRS 15 from the Nigerian perspective and challenges associated with the adoption. Four listed companies operating in IFRS 15 key impacted firms in Nigeria which accounts for 82% of total market capitalization as of April 2021 were selected. The data extracted were analyzed with the aid of tables, charts, ratios, percentages and content analysis. The study revealed that listed firms in Nigeria aligned with the need to adopt and fully implement IFRS 15 in their financial reporting in response to regulatory pressure and increased internationalization of their operations. The study, therefore, concluded that adoption and implementation of IFRS 15 had a positive effect on accounting numbers of listed firms in Nigeria. The study identified the proper identification and treatment of royalties, income taxes, proper delineation of revenues from contractual fees, the need for persistent contract modifications, capitalization of contract costs, and collectability issues, as key challenges of IFRS 15 implementation. The study recommended that the Board and Management of companies operating in the IFRS 15 impacted industries should always provide greater clarity on the basis used for arriving at the significant judgment calls they make. Also, the Financial Reporting Council and external auditors need to develop workable methodologies to monitor and tighten compliance with both quantitative and qualitative IFRS 15 disclosure requirements.