Exposure to xenobiotic chemicals through food and the environment is a growing concern for both humans and animals. Pesticides, used since 2500 BC to control pests and improve crop yields, persist in the environment, accumulating in soil, water, and living organisms. These chemicals pose significant threats to aquatic ecosystems, particularly impacting algal communities essential for ecological balance and primary productivity. While xenobiotics are toxic to algae, these organisms can accumulate and bioremediate these compounds, making them crucial in studies of environmental detoxification and ecosystem resilience. Understanding the interactions between xenobiotics and algae is key to assessing ecological risks and mitigating the impact of these pollutants. This chapter provides a comprehensive overview of the interactions between xenobiotics and algae, exploring the types of xenobiotics that affect algal communities, their uptake and toxicity mechanisms, and the key factors influencing these processes. By examining the adverse and adaptive responses of algae to these pollutants, this chapter offers critical insights into the complex dynamics at play. The goal is to enhance our understanding of xenobiotic-algal interactions and to inform the development of strategies for protecting and restoring aquatic ecosystems in the face of increasing environmental challenges.