Garcinol is a natural polyisoprenylated benzophenone extracted from the dried fruit rind of Garcinia indica. The aim of this study was to investigate the roles of garcinol in oral squamous cell carcinoma (OSCC) cells and its action on cancer cell energy metabolisms. Cell cycle, apoptosis, migration and invasion assays were detected, and oxygen consumption and extracellular acidification rates were also measured with Extracellular Flux Analyzer. Our studies showed that garcinol represses OSCC cells proliferation, cell cycle, migration and invasion, and colony formation. Of note, garcinol directly targeted cancer cell energy producing pathway mitochondrial respiration by significantly inhibiting ATP production, maximal respiration, spare respiration capacity and basal respiration in a dose-dependent manner. But garcinol treatment reflexively boosted glycolysis presented by increased glycolysis and glycolytic capacity. The promotion of garcinol on glycolytic pathway is also confirmed presented by elevated lactic acid content and the activity of pyruvate kinase. Furthermore, the expression of glucose transporter1 and 4, and several important genes related to the glycolysis pathway, including HIF-1α, AKT, and PTEN, was also upregulated after garcinol treatment. Taken together, our results revealed that garcinol has opposite effects on tumor energy metabolism through inhibiting mitochondrial oxidative phosphorylation significantly, and reflexively enhancing glycolysis in OSCC cells. Abbreviations OSCC oral squamous cell carcinoma DMBA dimethylbenzanthracene OCR oxygen consumption rate OXPHOS oxidative phosphorylation ECAR extracellular acidification rate.