The aim of this research is to examine the effects of Web 2.0 tools used in online education on the self-regulation perceptions of primary school fifth-grade students. For this purpose, the Sun, Earth and Moon units we processed online using Web 2.0 tools. The study was implemented in a public primary school over six weeks. The sample of the study consisted of 12 students (seven female and five male students) in the 10-11 age group. The mixed research method was used in the study. The "Perceived Self-Regulation Scale" developed by Arslan & Gelisli (2015) was used as a quantitative data for collecting information, and the "Semi-structured Telephone Interview on Self-regulation Perceptions" was used as a qualitative data collection tool. The quantitative data were analyzed using the SPSS program, and the qualitative data were analyzed using the content analysis method. The results of the study revealed that online education supported by Web 2.0 tools within the scope of the Sun, Earth, and Moon units had a positive effect on students' self-regulation perceptions.