Today, there is an increasing interest in digital games. However, using digital games in education has also come to the agenda. Supporting a problematic and tedious course such as mathematics, which is considered difficult and tedious, with games considered more fun, has been a subject of curiosity and practice for educators. In this study, pre-service mathematics teachers were asked to design digital games related to the objectives of secondary school mathematics courses. The study examines the effect of designing educational digital games on pre-service mathematics teachers' use of educational games, creativity and game development self-efficacy. The research lasted eight weeks. Single group pre-and post-test design, one of the quantitative research designs, was used in the study. The study sample consisted of 37 pre-service mathematics teachers enrolled in the second year at a state university. Data were collected with the help of three scales. SPSS was used to analyse the data. After the determination of normality, Wilcoxon signed rank test and paired sample t-tests were used. As a result of the research, it was seen that digital game designing did not significantly affect pre-service mathematics teachers' educational game use and creativity. However, it was determined that game designing significantly affected game development self-efficacy.