The present study explored EFL students' perceptions and experiences in utilising ChatGPT to seek feedback for writing. The present study also examined how levels of metacognitive awareness (MA) influenced these perceptions and experiences. Utilising a mixed-method research design, the study collected data from a total of 40 EFL undergraduates over a semester-long writing course. Data collection methods included self-report questionnaires and semi-structured interviews. Data analyses comprised both quantitative and qualitative approaches. Quantitatively, "t"-tests and Mann-Whitney "U" tests were used to compare group differences, while regression analyses were conducted to explore relationships between variables. Qualitatively, thematic analysis was employed to identify and interpret patterns within the data. Quantitative analysis revealed significant differences in writing experiences and perceptions, including motivation for writing, engagement, self-efficacy and collaborative writing tendency. Furthermore, a positive correlation was found between MA scores and students' perceptions and practices of using ChatGPT. Analysis of interview data highlighted a range of perceptions and experiences between the high and low MA students, with behaviours spanning from mere copying words from ChatGPT to effective use of ChatGPT for writing feedback. Key factors that influenced the effective use of ChatGPT for writing assistance included metacognitive awareness, critical thinking skills and cognitive efforts. The findings highlight implications for writing teachers and students in teaching and learning English as a foreign language.