Academic self-efficacy is an essential element for effective and engaging learning. In order to improve academic self-efficacy, students need to engage in regular and effective self-reflection to form realistic beliefs about their own academic capabilities. However, students may not be motivated to sustain effective self-reflection. Suitable tools are needed to assist students to self-reflect effectively. The objectives of this study were to determine the effect of writing personalized weekly e-learning journals on students' academic self-efficacy, the perception of its usefulness, and how it has helped students improve their academic self-efficacy. Multiple data collection methods were used in order to provide data for better explanations on the causality of the dependent and independent variables. Fifty-four students studying a degree program wrote personalized weekly e-learning journals over a ten-week period. Pre-tests and post-tests on their academic self-efficacy were administered in study week one and eleven respectively. The personalized weekly e-learning journals contained personalized prompts. The purposes of these prompts were not only to scaffold students to self-evaluate and self-reflective effectively but also to collect weekly time series data on academic self-efficacy and perceived usefulness in writing these journals. The post-test scores and time series data showed that the academic self-efficacy and the perceived usefulness of writing e-learning journals over the intervention period have improved. Writing personalized weekly e-learning journals has motivated the students to self-evaluate regularly, sustain their self-reflection, and promote positive academic self-efficacy. This study highlighted the benefits of writing personalized e-learning journals.