The study investigated the green human resource planning and organizational performance of plastic manufacturing firms in South-East, Nigeria. Specifically, the study has two objectives and two hypotheses. Relevant conceptual, theoretical and empirical literature were reviewed taking into cognizance problem and the hypotheses of the study. Anchored on Resource-Based Theory, this descriptive study conducted in South-East, Nigeria, utilized data from primary and secondary sources to study a population of 1929 employees from Plastic Manufacturing Firms. A sample size of 371 was determined using the Borg and Gall formula, and data was collected via a questionnaire whose validity was ensured through face and content validity, and whose reliability was established using the test-retest method and Cronbach's Alpha, prior to testing the hypotheses with Linear Regression Analysis. Green training and development had a positive significant effect on operational performance of plastic manufacturing firms (β =.243, t = 4.699, p=0.000<0.05). Green culture practices had a positive significant effect on environmental performance of plastic manufacturing firms. (β .164, t = 4.163, p=0.001<0.05) and green recruitment had a positive significant effect on product performance of plastic manufacturing firms in South-East, Nigeria. ( β=.178, t = -3.120,p=0.000<0.05. The study concluded that green human resources planning had a positive significant effect on organizational performance of plastic manufacturing firms in South-East, Nigeria. Plastic firms must adopt green training, focusing on emission control to enhance sustainability and operational performance. A strong pro-environmental culture is essential for success.