Motivation and good learning outcomes are important aspects that students must have. Several studies show that students have low motivation and learning outcomes. It is necessary to improve the learning model to overcome this problem. One of the efforts that can be taken is the application of the Chat Room-based Blended Learning model. This study aims to determine the effect of the application of the Chat Room-based Blended Learning model on student motivation and learning outcomes in the human respiratory system material. This is a Quasi-Experimental design with a Pretest-Posttest Non-Equivalent Control Group Design model. The research subjects were 68 students who were divided into two groups (experimental and control) where each group consisted of 34 students. The experimental group used the Chat Room-based Blended Learning model, while the control group learning was carried out using the Blended Learning model. This research was conducted at a high school in Meulaboh, West Aceh Regency, Indonesia. This research was conducted for two months (January-February 2020). The data collection parameters in this study were the learning outcomes and student motivation. Data collection was carried out through pretest and posttest. The test for differences in learning motivation and learning outcomes was analyzed using parametric statistics, namely the ANACOVA test. The results showed that the application of the chat room-based blended learning model had a positive contribution to increasing student motivation and learning outcomes. There needs to be a further study of the learning process with a chat room-based blended learning model.