The web-based portfolio emerged as a result of the influence of technological developments on educational practices. In this study, the effect of the web-based portfolio building process on academic achievement and retention is explored. For this purpose, a study platform known as a computer-assisted personal development portfolio was designed for 30 Turkish students who participated in a web-based portfolio process. The academic achievements of the students were examined through an experimental design in which participants were divided into an experimental group and a control group and given a pre-test and a post-test. The results of the study revealed that the levels of both academic achievement and retention in the experimental group were significantly higher than those in the control group. Similar practices can be applied to the teaching of medicine, economics, physical sciences, humanities and other subjects in order to extend students' performance and achievement levels.