Labu Siam and Labu Anggur exhibit different amount of antioxidant activities, phenolics, and flavonoids. Heating treatments including (boiling and steaming) as well as fermentation has been shown to increase the antioxidant activity. Thus, this study was carried out mainly to investigate the effect of chayote types, processing methods and fermentation length towards the antioxidant activities, phenolics and flavonoids. The analyses done were proximate analysis, DPPH-Free Radical Scavenging Assay for antioxidant analysis, Folin-Ciocalteau method for total phenolic content and aluminum chloride method for total flavonoid content. In all variables analyzed, Labu Anggur had significantly higher amount of mEQ/100 g fresh sample compared to Labu Siam. In terms of process, steaming and raw had significantly higher amount of antioxidant activities compared to boiled chayote. However in phenolic content, raw chayotes had significantly highest amount of phenolics (13.397±0.507 GAE/100g samples) compared to steaming and boiling. Different trend was shown in flavonoid content in which both steaming and boiling had significantly higher amount of flavonoid content compared to raw chayote. In the second stage, fermentation by kombucha culture up to 120 hours gave significant increase in both antioxidant activities and flavonoid content. The highest amount observed at the 120th hours. However for phenolic contents, there was only significant increase observed between 0 hours and 72th hours. Those results were due to probable breakdown of complex bioactive components to smaller bioactive component by heat treatment and kombucha enzymatic reaction.