Phytochemicals are broad, largely studied compounds isolated from plants, generally regarded as a research compound than a nutritive molecule. In recent times, the pharmaceutical industry employs plants in the synthesis of novel drugs and active ingredients. These drugs and ingredients effectively manage neurodegenerative disorders, metabolic diseases, cancer, obesity, and other chronic-degenerative diseases. Although it still remains to be elucidated, the therapeutic strategies in synthesizing novel compounds. In this review, we discuss the major classification of phytochemicals, in addition to its biochemical mechanism of action. Furthermore, this study detailed the biosynthetic cascade of various phytochemicals and explained the anti-inflammatory and antioxidant mechanism on various disease processes. Therefore, this review discusses the multifunctional bioactivity of phytochemicals. GRAPHICAL ABSTRACT