The 5E Learning Cycle Model (Bybee, 1990) is an instructional design model which has roots in inquiry-based learning and constructivism and has received much support in non-EFL-related literature as a way to improve 21st-century skills, such as critical thinking and creativity, among students and to prepare them for an amazing occupational future. However, little work has been done on the model concerning English language students; hence, this study dealt with the effect of 5E-based online activities on English language students’ critical thinking and creativity. The study utilized a mixed method grounded theory method approach. A sample of 60 adult English language students studying in a pre-IELTS class at a private language academy took part in the study during a 12-session semester, in addition to an extra session at the beginning of the semester, in which they received instruction with regard to the platforms to be used, namely Easyclass and Nearpod. Student interviews and self-reflections, teacher interviews, self-reflections, and field notes were applied to extract qualitative data, and student self-assessment checklists were used to gain quantitative data. The analysis of the quantitative and qualitative data via an independent sample t-test, inductive thematic analysis, and grounded theory demonstrated that the employment of 5E-based online activities culminated in the improvement of EFL learners’ critical thinking and creativity. The findings have theoretical and practical implications not only for 21st-century language practitioners’ education and competencies but also for curriculum development.