Tourism round the world has been a recognized phenomenon which is one of the fastest growing industries of socio-economic of nations, which Nigeria and Cross River State in particular are benefactors with evidence based, as one of the sources of Internal Generating Revenue (IGR), and infrastructure development, but the fact lies in the effective management of the sites for sustainability, and to achieve its goals, which is the hub of this study. The study adopted a survey design to examine the relationship between the effective management of tourism sites and sustainable economic growth and development in Southern Cross River State, Nigeria. Two research questions were posed, which were translated into two null hypotheses. The population for the study consists of eight viable tourism sites in Southern Cross River State, Nigeria, comprising of 8 curators and 34 administrative staff, and was used as sample for the study. The consensus sample size of 8 Curators and 34 administrative staff (making 42 sample size) was adopted due to the small population size, also to enable a good generalization of the findings of the study. The instrument titled “Effective Management of Tourism Sites and Sustainable Economic Growth and Development (EMTSEGD)” was developed by the researcher, validated by experts, and used for data collection. To determine the reliability of the instrument, 1 Curator and 4 administrative staff from one viable tourism site in Central Cross River State, yielded an average Cronbach Alpha index of .82. The hypotheses were tested using the Pearson Product Moment Correlation Coefficient at the .05 level of significance. The findings of the study revealed that the effective management of tourism sites significantly relates to sustainable economic growth and development in Cross River State, Nigeria. It therefore concluded that sustainable economic growth and development in Cross River State, Nigeria, also depend on the effective management of tourism sites. Based on these findings and conclusions of the study, it was recommended, most importantly that the government should create comprehensive tourism management plans that reflect diverse interests and will enhance both economic growth and development in local communities.