In developing an ESP writing course to prepare business administration students for business careers, it is essential to identify their English writing needs. Thus, this study aims to explore the English writing needs of Thai undergraduate business administration students as an initial step of ESP writing course development, highlighting four areas: their perceived writing abilities, writing challenges, required writing skills, and learning preferences. This study employed an interpretivist approach with a qualitative design, drawing on data from semi-structured interviews with 12 business administration students and 16 stakeholders, including employers, employees, entrepreneurs, ESP lecturers, and business lecturers. The findings reflect the learning experiences and insufficient English writing abilities of business administration students and graduates with problematic areas in grammar and vocabulary. In addition, they typically have problems with writing emails and reports. Specifically, three English writing skills were identified as required skills for business administration personnel, namely the skills to write emails providing information, e-commerce product descriptions, and progress reports. Student preferences for business vocabulary and communication expressions, teacher feedback, and a positive learning environment were revealed. This study offers educators and course designers valuable insights into the English writing needs of Thai business administration students for ESP course development.