Learner journals, diaries, and logs have been used in a variety of learning contexts, including foreign language learning. This paper investigates how diary writing can be used in the EFL classroom to encourage students to express their identities through the language they are learning; it is also a way of supporting them in their quest for greater autonomy, with a view to exploring the interconnections between learner autonomy, learner self (L2 self), and learner emotions. More specifically, it will be shown how reflective writing – in the form of online diaries – can offer learners an important tool to explore their thoughts and emotions and reflect on their identity as learners and users of English. Moreover, diaries are a qualitative research tool for teachers and scholars, who can examine metacognitive and affective aspects of language learning. The paper reports a study conducted within a university English Language course, in which the students were encouraged to keep a reflective online diary throughout a semester. The analysis of their personal and expressive writing has shed light on their need to speak as themselves, not just as language learners, and to explore their emotions, both positive and negative. A final questionnaire has revealed that the students were generally positive about the activity, highlighting its usefulness in terms of learner autonomy, self-awareness, and self-regulation.