In the virtual laboratory learning process, students' scientific abilities in solving a problem are very important to explore. This study aims to develop classroom-based authentic assessment instruments through virtual laboratory learning in chemistry to see an increase in students' scientific performance. The research was conducted at a public high school in Langsa City with a sample of 11th-grade students Academic Year 2021/2022, the utilized subjects being a total of 118 students taken based on purposive sampling. The research data are needs analysis through interviews with chemistry teachers who have implemented technology-based learning, analyzing the feasibility of instruments through expert validation questionnaires before the learning process, and scientific performance through learning observation sheets during the learning process. The increase in students' scientific performance data was then analyzed using the N-Gain formula and t-test to see the difference in improvement after the authentic assessment was applied. The results show that authentic assessment is feasible to use an increase in students' scientific performance. From the small-scale test, the students' scientific performance was a high category and there is a significant difference in improvement. The use of authentic assessment through virtual laboratories is expected to provide active learning solutions to improve student learning outcomes.