The study investigated the relationship between accounting standard adoption and financial reporting quality of public sector entities in Rivers and Bayelsa States of Nigeria. The study adopted survey and correlational research designs. The study population consisted of all public sector entities and a sample size of three hundred and twenty (320) was utilized for the study. Primary and secondary sources of data were employed while univariate, bivariate and multivariate analysis were used for data analysis. The multivariate analysis indicated that there was a relatively very strong positive and significant relationship between Post-IPSAS regime and relevance of selected public entities in Rivers State and Bayelsa State; there was a relatively strong positive and insignificant relationship between Post-IPSAS regime and faith representation of selected public entities in Rivers State and Bayelsa State; there was a relatively negative and insignificant relationship between Post-IPSAS regime and understandability of selected public entities in Rivers State and Bayelsa State and there was a relatively very negative and insignificant relationship between Post-IPSAS regime and timeliness of selected public entities in Rivers State and Bayelsa State. The study concluded that accounting standard adoption influences the quality of financial reporting quality of public sector entities in Nigeria. Therefore, the study recommended amongst others that public sector entities should adopt PostIPSAS principles in preparing their financial reports because this study affirmed that Pre and Post IPSAS has positive and significant relationship with financial reporting standard in term of relevance of quality.