This study carried out an appraisal of the National Social Investment Programme and Economic Development in Nigeria: A Case Study of Bayelsa State, 2015-2022. The study adopted the correlational research design to enable the researcher to establish the relationship between the dependent and independent variables. The target population for the study is estimated to be around two hundred and fifty thousand children, youths and women (250,000) in Bayelsa State. Taro Yamane formula was used to determine the sample size of 399 drawn from the total population. An instrument titled; “Appraisal of National Social Investment Programme and Social Economic Development Questionnaire” (ANSIPSEDQ) was developed to elicit data from respondents which were validated and its consistency tested using Cronbach Aphla and the result yielded 0.86. Out of the 399 (100%) questionnaires distributed, 382 (95.7%) were returned valid, while 7(4.3%) copies of the questionnaire were discarded due to filling errors. Pearson Product Moment Correlation (PPMC) was used to test the null hypotheses at a 0.05 level of significance with the aid of Statistical Package for Social Science (SPSS) Version 26.0. Findings from the study revealed that the National Social Investment Programme through the N-Power Programme, Government Enterprise and Empowerment Programme, National Home-Grown School Feeding Programme and Conditional Cash Transfer enhanced economic development in Nigeria. Based on the findings, it was concluded that National Social Investment Programmes, enhance economic development in Nigeria: a case study of Bayelsa State, 2015-2022. The study recommended, among others, that the federal government of Nigeria should stop the delay in payment of the N-Power stipend to avoid its negative effect on human capital and economic development, combat high illiteracy, low education, lack of skills training, and scarce facilities and resources among children, youths and women in Nigeria for effective implementation and actualization of the Government Enterprise and Empowerment Programme goals.