This study investigated how cooperative learning affected students' academic performance in an online higher education environment. Its specific goal was to find out whether, in comparison to conventional online learning techniques, including cooperative learning activities could improve academic achievement. An experimental control group with a pre-test and post-test design was used. All students enrolled in the Virtual University of Pakistan's Fall semester undergraduate course" Test Development and Evaluation" were included in the population. A sample of seventy-three students was chosen and split into two groups: a control group consisting of 38 participants and an experimental group consisting of 35 individuals. In order to incorporate cooperative learning into the online learning environment, email-based activities were carried out. The purpose of these activities was to promote cooperation and knowledge exchange among the students in the experimental group. Contrarily, the control group followed the typical online learning protocol, finishing the pre-and post-tests but forgoing the cooperative learning exercises. The achievement exam functioned as the pre-test and post-test tool, enabling researchers to evaluate modifications in students' comprehension and knowledge. To compare the gain scores (the difference between pre-and post-test scores) between the experimental and control groups, parametric statistical analysis was used, most especially t-tests. A specified significance criterion of p< 0.05 was established.