Design thinking (DT) could provide a viable method to develop 21st-century skills in English as Foreign Language (EFL) classrooms; however, its potential is not clearly understood. To explore this potential, two Japanese university teachers developed a DT course in which students built a creativity measure and wrote academic reflections. Student work displayed creative thinking, insight, and language play. Survey data revealed correlations between DT, student enjoyment, confidence communicating, and thinking flexibly. In conclusion, DT can facilitate collaborative engagement and creative thinking, however, time to develop on-task communication and a focused approach to report writing may be necessary to support understanding and communicative competence.