A contradiction between the Ethiopian law of investment and environmental law is prevalent since law of investment promotes development while environmental law protects the environment. The thesis investigates the general legal issue: How do the investment and environmental laws of Ethiopia promote large-scale agricultural development without adversely affecting the environment? In the research, comparative legal research methodology is employed: comparison is made between the internationally accepted principles of large-scale agricultural investment and Ethiopian laws; the laws and experiences of Brazil and South Africa are showed that law of sustainable large-scale agricultural investment is vital to promote agricultural development and protect the environment. International law on investment and environment are also considered. International legal principles of solving the contradiction between environmental law and investment law are analysed. Legal and document analysis of Ethiopian laws, policies and government documents have been made. Interviews have been made, data through questionnaires have been collected and analysed, and 12 large-scale agricultural investment farms have been observed and critically analysed. The thesis identified that law of large-scale agricultural investment promotes development while Ethiopian environmental law protects the environment. The law has a role in promoting large-scale agricultural development by recognising the right to development and providing incentives and creating conducive environment. Thus, the law should be used to promote both the right to development and environmental protection. The nexus between investment law and environmental law should be strengthening. It is identified that the law of sustainable large-scale agricultural development could protect the environment while promoting large-scale agricultural development. The thesis identified the Ethiopian law and the practices do not promote sustainable large-scale agricultural development. Thus, it is recommended that precautionary principle, like EIA should be made a requirement for large-scale agricultural investment, implementing efficiently and effectively the large-scale agricultural law principles, and laws to achieve sustainable large-scale agriculture. / Public, Constitutional and International Law / LL. D.