Recent research has highlighted the value of incorporating metacognitive prompts into cooperative learning. This study explores effects of the presence or absence of metacognitive prompts in group or individual learning on metacognitive awareness and EFL writing outcomes. A total of 170 university students were assigned to one of four treatment conditions: collaborative learning with metacognitive prompts (COOP + META), collaborative learning without metacognitive prompts (COOP), individual learning with metacognitive prompts (INDI + META), and individual learning without metacognitive prompts (INDI). After treatment, learners exposed to metacognitive prompts in a cooperative learning setting outperformed the other groups in metacognitive awareness and EFL writing. Multiple regression analysis also showed that enhanced metacognitive awareness significantly predicted English writing outcomes. Results revealed metacognitive regulation was a more significant predictor of writing outcome. These findings highlight the importance of incorporating metacognitive prompts within collaborative writing settings.