Objective: In this study, I investigate the efficacy of Microsoft (MS) Teams Class Notebook e-portfolios as a reflective tool in business writing courses. I address gaps in the literature regarding e-portfolio use in business writing courses in face-to-face classes, focusing on student perceptions, the impact of e-portfolios on writing skills, the convenience of the MS Teams Class Notebook, and how it fosters critical thinking regarding their learning, which is one of the important goals of education for sustainable development (ESD). Methods: I conducted the iterative cross-sectional study during more than 13 weeks at a private college in Oman with 60 undergraduate students in two business writing classes. Data were collected using a mixed-method approach composed of a 5-point Likert scale questionnaire from 44 participants. I performed quantitative analysis via frequency-based scaling. Qualitative insights were derived from lexicon-based sentiment analysis using VADER. Results: The quantitative findings revealed that 75% of students perceived e-portfolios as valuable tools for reflection, skill development, and understanding strengths and weaknesses. A majority also reported improved confidence in using technology. Qualitative sentiment analysis supported these findings, showing predominantly positive feedback, although students noted some challenges, including process complexity. Conclusions and Implications: The study concludes that e-portfolios effectively enhance student learning outcomes in business writing courses, particularly in fostering reflection and critical thinking. Despite some challenges, such as initial complexity, the findings highlight the e-portfolio's potential as a transformative educational tool. My recommendations include providing adequate support during implementation and expanding research to include larger cohorts and diverse instructional contexts.