Online professional teacher development needs to be carried out on an ongoing basis by adjusting the needs of teachers in developing the quality of learning. In the preliminary survey, it was found that there is a high need for teachers to master mathematics content and methods of teaching mathematics so that it is easier for elementary school students to understand so that the goal of learning mathematics can be achieved optimally. This study aims to evaluate the effectiveness of the implementation of Online professional development and see the results and impacts that have been carried out to answer the needs of teachers for mastery of mathematics content and methods of teaching mathematics. Data was collected through questionnaires and interviews given to sixteen elementary school mathematics teachers in grade six at Lentera Harapan School spread across various provinces in Indonesia and then analyzed by statistical analysis using the Wilcoxon test. Online professional development has a significant impact on teachers to answer the need for mastery of mathematics content and mathematics teaching strategies for elementary school student. Teachers expect that online professional development will answer the needs of teachers to be carried out on an ongoing basis.