The purpose of this study was to examine the effect of GeoGebra software on pre-service teachers' mathematical connection skills. The participants of the study comprised 22 pre-service mathematics teachers. A mathematical connection self-efficacy scale and an open-ended questionnaire regarding mathematical connection skills were used as data collection tools. The implementations undertaken with the participants lasted 13 weeks in the dynamic learning environment. After GeoGebra implementations, the quantitative data were analyzed using a dependent t-test and the qualitative data obtained with the open-ended questionnaire were analyzed using descriptive analysis. Based on the results, it was determined that GeoGebra software could be used as an important tool for the development of mathematical connection skills.