This study examined teachers’ classroom practices for teaching English writing in secondary schools in Nigeria. The study was informed by evidence from Secondary School Certificate Examination results and personal observation, which revealed a high failure rate among students in English Language in terminal examinations, with the writing section accounting for a significant proportion of these failures. Grounded in social constructivism, the study was guided by four research questions and employed convergent mixed-methods research design. The study was delimited to teachers in public secondary schools in Edo State, Nigeria. Sixty-eight (68) teachers completed an online survey, while five (5) teachers who participated in the survey volunteered for semi-structured interviews. Data from the closed-ended questionnaire items were analysed using descriptive statistics of frequency count and percentages while the data from open ended responses and semi structured interviews were analysed using reflexive thematic analysis. The findings revealed that writing is perceived by teachers as a complex but necessary skill for every learner, and that teachers utilised the combination of product and process teaching approaches while they identified limited instructional time, variation in students’ writing proficiency levels and large classroom size as the major factors contributing to students’ poor writing performance. The study concluded that teachers in the investigated secondary schools demonstrate foundational understanding of the importance of writing instruction but face challenges in supporting students’ learning due to the identified limitations. It was, therefore, recommended that teachers address students’ weak writing foundations and low confidence in writing by adopting contemporary instructional support strategies. Additionally, the Ministry of Education should provide continuous professional development opportunities to enable teachers to align their practices with contemporary best practices for writing instruction.