Conservation agriculture (CA) improves crop-water and energy productivity, profitability, environmental quality, and preserves natural resources for future food security and poverty reduction. However, weeds are a major challenge for large-scale CA adoption. Changes in tillage and planting systems in CA shift weed populations, favouring small-seeded and perennial grasses. Weeds like Trianthema portulacastrum and Cyperus rotundus in direct-seeded rice, and Rumex dentatus, Medicago denticulata, and Avena ludoviciana in wheat, become more common, though Phalaris minor declines. Weed management, especially early in CA adoption, heavily relies on herbicides like paraquat, glufosinate ammonium, and glyphosate. However, crop residues can reduce herbicide efficacy, and overuse can lead to herbicide resistance. These problems are further exaggerated under the changing climatic scenario which requires deeper knowledge and understanding. Since C₄ weeds are more competitive, therefore, would be dominant under elevated temperatures and pose yield penalties. Under changing climatic scenarios such as increased temperature, delayed or late onset of rainfall, prolonged drought and elevated CO₂ levels are major concerns for weed management and crop production. Therefore, sustainable CA requires integrated weed management using both chemical and non-chemical approaches.