The study on business ethics practices in organization: A key to sustainable development in selected banks in south east Nigeria was motivated by the need to provide solutions to the problem of sustainability and business ethics practices in organization: key to sustainable development in banking industry in south east Nigeria. The study set out to accomplish the two specific objectives from which appropriate research question and hypothesis were postulated. The study adopted survey design. The population of the study was staff of selected banking industries in Abia state, Anambra state, Ebonyi state, Enugu state and Imo state in South East Nigeria. A sample size of 337 staff was determine from the total population of 2148 population using Taro Yamani sampling technique. The hypothesis were tested using regression analysis with the aid of statistical package for social sciences (SPSS) version 20. The major findings of the study were that ethical value has a significant positive effect on sustainable development of an organisation. There was a significant positive relation between customer loyalty and sustainability of an organization. The study recommended that the top management should invest in human capital in the area of modern banking system and that because of globalization on the job training has to gain way to out sourcing for best practices in global banking industry