The changes and developments in science and technology around the world have resulted in changes in expectations from teachers, because new skills are added such as digitalization of instruction which teachers are expected to possess in the 21st century. The use of Web 2.0-based tools in the field of education offers an alternative to traditional classroom teaching-learning environments. Producing, modifying and sharing information paves the way for Web 2.0 tools to be used in the learning and teaching process. This research aims to analyze the effect of Web 2.0 tools on pre-service classroom teachers’ science teaching self-efficacy beliefs and attitudes towards science teaching. This study is an experimental study and study group includes 79 preservice teachers studying in Primary School Teaching Department in the 3rd grade during the 2018-2019 Fall Semester. Participants are included in the study by using purposeful sampling method. The first data collection tool is “Science Teaching Self-Efficacy Belief Scale” and second instrument used is "The Science Attitude Scale". Due to lack of normal distribution, statistical techniques such as Mann-Whitney U and Wilcoxon signed rank test have been used in the study. As a result of analysis, there is no distinction between groups in the beginning in terms of science teaching self-efficacy beliefs and attitude towards science teaching. There is observed an increase both in the control group and experimental group; however, there is a statistically significant difference in favor of experimental group in the post-test measurements. The use of Web 2.0 tools lead to more positive change in pre-service classroom teachers’ science teaching self-efficacy beliefs and attitudes towards science teaching. In line with this result, it can be claimed that the instruction applied to the control group is also effective; but the use of Web 2.0 tools are more effective on science teaching self-efficacy beliefs and attitude towards science teaching.