The goal of vocational high schools (VHSs) in Taiwan is to offer VHS students a learning environment that combines professional knowledge with practical skills. However, VHS English education seems to have failed to achieve this goal because English has been taught as a subject rather than as a communication tool. To bridge the gap between learning in schools and demands in the job market, an intensive task-based English for Special Purposes (ITB ESP) program was developed for the purposes of this study to link students' professional knowledge and English skills to the workplace. Twenty-four VHS students were recruited as learning participants to make business PowerPoint (PPT) presentations for workplace purposes. The participants were engaged in making presentations four times (pre-instruction, after-instruction, pre-workplace and post-workplace presentations) and making changes based on instruction and suggestions from different stakeholders (teacher-learners, teachers of business and Applied Foreign Languages (AFL) and workplace supervisors). Both qualitative and quantitative data were analyzed to assess how students' conceptual understanding of and skills related to conducting and delivering PPT presentations evolved over time. The results show that the ITB ESP program had a significant impact on VHS students’ concepts and skills related to making English business presentations. Grounded in the curriculum design process model (Nation & Macalister, 2010), this study identified critical factors contributing to the effectiveness of the program. This study concludes with important implications for ESP curriculum development and collaboration between industry and academia.