The growth of Thailand's medical tourism industry has inevitably made English oral communication skills become increasingly important to Thai medical personnel, especially to nurses who have to act as medical mediators between doctors and patients. Thus, in order to prepare nursing students for their future career, it is necessary that English teachers find a way to help students improve their oral communication ability. Thus, in this study, as a means to overcome the students' difficulties in learning English and to enhance their English oral communication ability, the task-based instruction using a digital game in a flipped learning environment (TGF) was developed by integrating three language learning approaches, namely task-based language teaching, flipped learning, and digital game-based language learning. The development of the instructional framework for the TGF was described first. Then, to investigate its effectiveness in improving the students' oral communication ability, an experimental study, using a one-group pretest posttest design, was conducted with 23 second-year nursing students at a private university in Thailand for 11 weeks. The effects of the TGF on the students' oral communication ability were assessed by the participants' pre- and post-test. The finding revealed that the participants' average post-test score was statistically significantly higher than their average pre-test score (p < 0.05), indicating that the TGF was successful in enhancing the students' oral communication ability. Lastly, the factors contributing to this success were discussed.