The current study investigated the writing errors made by Saudi female EFL learners, focusing specifically on analyzing their English writing using an error analysis framework. It aimed to identify the most frequent types of writing errors, determine the underlying causes of these errors, and propose effective strategies to help learners improve their writing proficiency. The study employed a mixed-method design consisting of a writing test and a questionnaire. The writing test was used to analyze the linguistic, grammatical, lexical, syntactical, and mechanical errors in the learners’ written paragraphs, while the questionnaire provided insights into the learners’ perceptions of the difficulties they face, the factors contributing to their writing errors, and the instructional practices that may influence their writing development. The study sample included 33 Saudi female EFL learners in their fifth level at the College of Languages and Translation at Najran University. The study findings revealed that the learners frequently made a wide range of writing errors, with spelling mistakes, punctuation errors, capitalization problems, incorrect verb tenses, subject-verb agreement issues, and article misuse being the most common. The findings also showed that L1 interference, particularly the transfer of Arabic sentence structures and vocabulary patterns, played a major role in shaping these errors. Additionally, factors, such as limited English proficiency, insufficient writing practice, inadequate feedback, and traditional teaching methods contributed to the persistence of these writing difficulties. According to the findings, the study recommends integrating regular writing practice, providing explicit grammar instruction, offering timely corrective feedback, and utilizing technology-based tools to support writing accuracy. It further suggests that curriculum designers incorporate writing workshops, peer review opportunities, and contrastive analysis activities to help learners better understand the differences between Arabic and English writing systems.