This study aims to analyze and examine the effect of the application of the blended learning model on mathematics learning outcomes. The research hypothesis being tested is the effect of the blended learning model on student learning outcomes in Mathematics at SDN 1 Pajerukan. The research was conducted using an experimental method. The sample size is 44 students, with the sampling technique used is cluster sampling. The research instrument used is a test of Mathematics learning outcomes in the form of a description with 5 options and 5 multiple choice which have been tested for validity with a reliability coefficient = 0.367. Data analysis using Paired Sample T-Test. The results of hypothesis testing obtained the following conclusions: There is a significant effect of the blended learning model on student learning outcomes in Mathematics at SDN 1 Pajerukan. With the acquisition of the results of the calculation of the posttest hypothesis test through a t-test at a significant level of 0.05, the results obtained ttable < tcount or 5.813> 1.7011, so it can be concluded that Ha is accepted. The results of this calculation prove that there is a significant effect of learning using the blended learning model. The results obtained in this study can be concluded as follows that there are differences in mathematics learning outcomes between students who take blended learning and students who take conventional learning. The average score of students' mathematics learning outcomes who took blended learning was higher, namely 85.55 than the average score of students' learning outcomes who took conventional learning, which was 77.5.