—This study aimed to examine the effectiveness of mobile blended compared to conventional problem-based learning on mathematical problemsolving skills and look for students' responses about the use of online learning. The study was conducted using a pretest-posttest quasi-experimental research design supported with descriptive qualitative responses involving 188 students taken by applying cluster random sampling as subjects of research distributed from vocational high schools in Bojonegoro City, East Java, Indonesia. Research findings revealed that mathematical problem-solving skills for students treated with mobile blended problem-based learning were higher than those who have been treated with purely problem-based learning. In addition, students have responded positively to the usage of mobile blended problem-based learning that was applicable and acceptable for effectively improving mathematical problemsolving skills.