Invasive plants, often seen as nuisances to ecosystems and agricultural practices, can be a source of valuable phytochemicals with immense potential for health applications. These plants, forced to adapt to harsh, competitive environments, have evolved unique chemical profiles as survival strategies. Their secondary metabolites, which are produced to deter herbivores, compete with other plants, or withstand environmental stressors, offer a rich and untapped source of bioactive compounds. Invasive plant phytochemicals exhibit a wide range of pharmacological properties, including antioxidant, anti-inflammatory, antibacterial, and especially anticancer activities. By understanding their chemical composition and biological activities, researchers can develop innovative strategies to harness their therapeutic potential while mitigating their ecological impact. This chapter explores the diverse phytochemicals found in common invasive plants and discusses innovative strategies for harnessing their biological activities.