The development of the oil industry in developing countries requires effective mechanisms for technology transfer through international cooperation. The purpose of this study is to examine the legal planning challenges of joint investment contracts for technology transfer in line with sustainable development in Iran’s oil industry. The research adopts a descriptive–analytical method based on library studies and analysis of legal sources, contractual frameworks, and legal doctrines. The findings indicate that technology transfer in joint investment contracts in Iran’s oil sector faces several challenges, including ambiguity in contractual obligations related to technology transfer, imbalance between the interests of foreign investors and national interests, limitations arising from intellectual property rights, weaknesses in regulatory and supervisory institutions, and insufficient attention to sustainable development requirements. These challenges often result in limited or superficial technology transfer and hinder the strengthening of domestic technological capabilities. The study concludes that improving the legal framework of joint investment contracts by defining clear and measurable technology transfer obligations, establishing effective monitoring mechanisms, strengthening collaboration between industry and academic institutions, and emphasizing environmentally sustainable technologies can significantly enhance technological capacity in Iran’s oil industry while aligning it with sustainable development objectives