Writing anxiety is a significant barrier to developing proficient English writing skills among EFL learners, particularly in the Iranian context. The present study was an attempt to address (i) EFL writing anxiety by developing and validating a context-specific writing anxiety questionnaire for Iranian EFL learners and (ii) the limitations of the existing measurement scales that are not tailored to the Iranian EFL context. To this end, the results of previous research on the attitudes of EFL learners were used to construct the EFL Writing Anxiety Questionnaire (EFLWAQ), which capture the multifaceted nature of writing anxiety, encompassing emotional, cognitive, and behavioral dimensions. A sample of 1061 EFL learners were selected from among EFL learners studying English language at five institutes of Kabir Academy, Kandoo, Gama, Pazhuhesh, and Sedaye Tabriz starting on April, 2023.  The sample was divided into two separate samples: one for exploratory factor analysis (n = 232) and the other for confirmatory factor analysis (n = 829).  The study was based on the correlational research design. An initial pool of items was refined through content validity analysis, achieving acceptable CVR and CVI scores. The initially validated questionnaire was then distributed to EFL learners in order to find the main factors of Iranian language learners' writing anxiety. The factor-analytic approach revealed a multi-dimensional structure of writing anxiety, identifying the key factors of Behavioral, Physiological, Cognitive, Maladaptive, and Emotional. It also confirmed the model fit, with all factors demonstrating high internal consistency. Findings indicate that the EFLWAQ is a reliable and valid instrument for measuring writing anxiety among EFL learners. The study’s outcomes provide valuable insights for educators, researchers, and policymakers to enhance English writing instruction and support learners in overcoming writing anxiety.