In the past two years, technology has been evolving rapidly due to the pandemic outbreak in the whole world, and invoking a significant surge in usage of education technology. During thesetimes, both teachers and students have been gradually becoming digital natives in carrying out teaching-learning process. The objective of this study is to investigate the use of Content-Based Instruction (CBI) in improving vocabulary mastery on the writing skills utilizing technology-enhanced language teaching into the learning. It was a qualitative approach study, where the participant' writing documents were evaluated by two raters employing a standard analytic rubric for assessing the vocabulary on the English Language Learner (ELL)' writings. Moreover, unstructured interview was performed as data triangulation. The findings revealed that there had been a substantial improvement on the learner' vocabulary size. The learner' writing competence developed since the words used within the writing documents were varied, and in accordance with the topic discussed. There was also a positive and moderate relationship occurred between teachers and learner that increased the creative learning and innovative teaching for both in using the technology. Future research can look into how CBI can affect learners' vocabulary learning either through synchronous or asynchronous.