It is known that a significant portion of the world's child population is gifted. Studies on the applications that can be used in the education of these gifted students have been given importance in recent years. In this study, the effect of differentiated instruction method on mathematics problem solving attitude and critical thinking skills of gifted students at primary school level was examined. The research is a pretest-posttest one-group quasi-experimental study. The study group consisted of five elementary school students diagnosed as gifted in Antalya/Turkey. "Mathematics Problem Solving Attitude Scale" and "Critical Thinking Scale" were used as data collection tools. The study continued for eight weeks, three hours a week. Throughout the study, problem solving instruction with differentiated method was carried out by the researcher. Within the scope of the study, quantitative data were analyzed using SPSS statistical package program. There was a significant difference between the pre-test and post-test of the mathematics problem solving attitude and critical thinking scales in the students. According to the results, it was concluded that there was a significant difference in the participants after the application. Therefore, it is possible to mention that individualized and differentiated education should be included in the mathematics problem solving attitude and critical thinking skills of gifted students due to its positive effect.