This study aims to develop a process-based English writing model for pre-service teachers. It also investigates how their conceptualization of English writing has changed and how they developed as English writers when the model was applied in an elementary pre-service teacher education course. The participants were 23 undergraduate students who registered in an academic writing course. Pre- and post-survey responses, academic writing self-assessment, writing artifacts (4 paragraphs and 1 essay writing), writing portfolios, and field notes were primarily collected. The data were qualitatively analyzed using content analysis. The results are as follows: first, the process-based English writing model was organized into preparation, implementation, and reflection stages. Pre-writing, drafting, revising, editing, and publishing stages were applied for each paragraph and essay writing task. Second, the participants’ conceptualization on English writing was changed into carefully planned, openly shared, and continuously developed writing. Third, the participants displayed cognitive, affective, and metacognitive development as English writers. Their writing skills, confidence, and motivation in English writing as well as writing management skills were improved. It was suggested that effective teacher education programs for promoting teachers’ writing skills should be developed and implemented. Further important implications regarding teacher development in English writing and teaching writing were discussed.