Heat the vegetable oil in a large skillet or wok over medium-high heat. Add the minced garlic and sliced chilies and stir for 30 seconds until fragrant.
Add the sliced chicken thighs and cook, stirring often, for 5 to 6 minutes until the chicken is browned and cooked through.
Stir in the oyster sauce, soy sauce, fish sauce, and sugar. Cook for another 1 to 2 minutes, tossing everything to coat the chicken evenly.
Remove the skillet from the heat and stir in the Thai basil leaves until they just begin to wilt.
Spoon the stir-fry over the cooked jasmine rice and serve right away.