Herbicide resistance is a growing issue in Southeast Asia’s agricultural systems. This chapter reviews current trends and challenges related to herbicide use and resistance in the region, focusing on major crops like rice, oil palm, rubber, corn, banana, cassava, and vegetables. It examines the prevalence and spread of resistant weed species in countries such as Malaysia, Thailand, Indonesia, and the Philippines, with some attention to Vietnam, Cambodia, and Laos. Factors driving resistance include such as the overuse and misuse of herbicides, lack of crop rotation, herbicide rotation and herbicide mixture with different modes of action, and insufficient integration of non-chemical control methods. The review highlights the impact of resistance on agricultural sustainability and calls for integrated weed management practices and policy reforms. Recommendations for future research and strategies to combat resistance are provided to support sustainable farming systems in the region.