Weeds remain one of the most persistent constraints to agricultural productivity and sustainability in Vietnam. Their high genetic diversity, adaptive reproductive strategies, and capacity for rapid evolution under intensive management regimes enable them to outcompete crops for light, nutrients, water, and space. In rice-based systems, particularly wet direct-seeded rice (WDSR), yield losses from dominant species such as Echinochloa crus-galli, Leptochloa chinensis, and weedy rice (Oryza sativa f. spontanea) can reach 30–80% if unmanaged. Beyond direct yield reduction, weeds aggravate pest and disease incidence, contaminate grain, and drive escalating production costs. The increasing prevalence of herbicide resistance linked to overreliance on a narrow set of chemical modes of action further challenges conventional control strategies. This chapter synthesizes current knowledge of weed biology and ecology in Vietnam, emphasizing seed dormancy, soil seedbank dynamics, vegetative propagation, and adaptive mechanisms underpinning resistance. We highlight region-specific weed diversity across rice, upland, orchard, and industrial cropping systems, and evaluate the ecological and economic impacts of weed infestations. Building on this biological foundation, we critically examine integrated weed management (IWM) strategies combining cultural, mechanical, chemical, and biological tools. Particular attention is given to allelopathic crops (e.g., rice, cucumber, cosmos) and plant-derived herbicides as emerging sustainable alternatives. Advances in digital agriculture, including artificial intelligence, remote sensing, and precision herbicide application, are also discussed as future pathways. By integrating ecological insights with innovative technologies, Vietnam has the potential to transition from chemically dependent weed control toward resilient, climate-adaptive, and environmentally sound management systems.