This research aimed to evaluate the environmental performance of selected bioplastic product produced from polylactic acid (PLA) and polybutylene succinate (PBS) based on life cycle approach. Raw materials used to produce bioplastic were cassava and sugarcane and garbage bag was selected as a model product to study. The environmental performance was then compared with the same product produced from conventional plastics (HDPE, LDPE, LLDPE). The scope of the study covered the entire life cycle of the bioplastic product, including plantation, harvesting, resin production, plastic processing, product use and disposal of the bioplastic product in Thailand. Initiated as the National Innovation Agency (NIA) pilot project, Sa-med island was selected as a model to study the use and disposal of bioplastic product by composting. The functional units were 1 kg bioplastic resin and 1 kg bioplastic product. The data were compiled and analyzed using SimaPro 7.0 with the CML baseline 2000 and the Eco-Indicator 95 methods to identify the environmental burdens with a focus on global warming potential (GWP). The cradle-to-gate results showed that GWP of PLA resin was lower than GWP of conventional plastic while the GWP of PBS was higher than GWP of conventional plastic resins, but it could potentially be reduced by applying practical improvement option. When the whole life cycle environmental impact of bioplastic was considered (cradle-to-grave), the results obtained using Sa-med island as an experimental site show that the performance of bioplastic in term of GWP is better than conventional plastics and composting is an appropriate waste management to gain highest environmental benefits from bioplastics.