Sinensetin, a polymethoxylated flavone abundant in citrus fruits, has been recognized for its broad biological activities and wide use in traditional medicine around the world. Emerging clinical evidence from flavonoid-enriched orange juice interventions indicates antioxidant and anti-inflammatory effects, aligning with extensive preclinical data. In this review, we explored in vitro and in vivo findings on the anti-inflammatory and anticancer actions of sinensetin and delineated the underlying cellular pathways, especially in terms of proposed targets for sinensetin. In inflammatory settings, sinensetin attenuates NF-κB activation, lowers pro-inflammatory cytokines (e.g., TNF-α, IL-6), and enhances antioxidant defenses, supporting its reported antioxidant, anti-bacterial, anti-viral, and anti-obesity properties. Across multiple tumor models, sinensetin suppresses oncogenic signaling-including β-catenin, PI3K/AKT, VEGF, NRF2, P53, and MKK6-concomitant with reduced proliferation, migration, and survival signaling. We further discuss emerging immunological effects, including modulation of innate immune cell activation and cytokine production, which may contribute to tumor microenvironment reprogramming and inflammation resolution. Together, these mechanistic insights position sinensetin as a promising lead for chemopreventive and adjunct therapeutic strategies. Our efforts aim to provide insights into the future translational development and clinical evaluation of sinensetin and its derivatives.