It is well accepted that not only the ability but also the positive disposition of teachers towards implementing differentiated teaching for various student groups can be traced back to their initial education. Therefore, differentiated practices of future teachers for high-achieving students are worth exploring. Based on the above, the purpose of the current study is to explore the practices and reflection of future teachers on differentiated teaching for high-achieving students. The participants (N = 142) were undergraduate students of a Greek university, who, during a six-month compulsory practicum course, planned and implemented in schools a two-hour-long differentiated course. In particular, their differentiated teaching strategies used for high-achieving students were investigated, as well as their reflection on the effectiveness of these strategies. Data were collected through the participants' responses to the course's open-ended evaluation form. Data were analysed on a mixed-methods basis (quantitative and qualitative) by two independent raters. Main findings have shown that the participants differentiated mainly the process of teaching according to their students' learning readiness. Specifically, they provided less or lack of support for their high-achieving students, creating activities with a higher level of difficulty as well as activities that activated higher-order thinking skills. Finally, they believe that their strategies mostly affected their students' learning/cognitive domain.