Weeds pose a significant threat to agricultural productivity. Bangladesh is a tropical country where weeds severely affect different crops, leading to substantial economic losses for farmers. Understanding the biology of a particular crop’s most prevalent weed species is crucial to developing targeted management strategies. This chapter explains the biology and management of the most common weed species in five important crops: rice, corn, jute, sugarcane, and onion, considering their economic value and weed management significance in Bangladesh. Rice is a staple crop, covering over 75% of cultivable land, making it one of the most important crops in Bangladesh. The yield losses from weed infestation in rice range from 15% to 100%, depending on the season, establishment methods, types of weed infestation, land position, and farmers’ weed management practices. Chemical weed control with herbicides is becoming popular in Bangladesh for its cost-effectiveness and labor efficiency. However, relying solely on chemicals is not a sustainable long-term strategy. Farmers’ understanding of weed biology can enhance integrated management approaches for better sustainability. Corn is currently the most promising crop in Bangladesh, but weed infestation can lead to yield losses of 30%–50%, posing a threat to crop productivity. The yield losses in jute, sugarcane, and onion due to weeds have been 90%, 20%–70%, and 40%–80%, respectively. This chapter outlines the biology of major weeds and various management practices, including integrated approaches for specific crops. It serves as a valuable resource for farmers, researchers, and policymakers aiming to understand and manage weeds in key Bangladeshi crops.