Objective: Mangosteen rind (Garcinia mangostana L) is a plant that is quite popular in Indonesia. Mangosteen rind extract contains alpha-mangostin. Poor water solubility of alpha mangostin limits its oral bioavailability. The formulation in the form of SNEDDS is expected to increase the solubility and bioavailability of the active fraction of mangosteen rind. Dichloromethane (dcm) fraction has high antioxidant activity so it is used as an active substance in SNEDDS formulation. To optimize a self-nanoemulsifying drug delivery system (SNEDDS) to enhance solubility, dissolution, and oral delivery of alpha mangostin. Methods: Solubility screening was performed in various oils, surfactants, and co-surfactants. The optimized SNEDDS was evaluated for droplet size, PDI, zeta potential, and stability under centrifugation, heating–cooling, and freeze–thaw cycles. Dissolution studies were conducted in vitro, and cumulative release profiles were analyzed kinetically. Results: The optimized SNEDDS (1.64:7.34:1.02, isopropyl myristate: Tween 20: propylene glycol) formed nanoemulsions with droplet size 50.6±1.37 nm, PDI 0.206±0.0036, and zeta potential-15.35±0.81 mV. Stability tests showed no significant change after stress conditions. Transmittance was 70.125%, indicating adequate clarity. Dissolution was significantly improved compared to dcm fraction. The R2 calculation results obtained for the zero-order data were 0.5882, first-order 0.8852, Higuchi 0.6945 and Korsmeyer-Peppas 0.8556. Therefore, it can be concluded that the release kinetics for the dcm fraction of SNEDDS follows a first-order model, with the R2 value approaching 1. This means that the drug release rate is directly proportional to, or dependent on, the remaining drug concentration in the dosage matrix. Conclusion: Optimized SNEDDS improved dissolution and demonstrated robust physical stability under stress conditions, highlighting its potential for oral delivery of α-mangostin. © 2026 The Authors.