Prior research studies have extensively used different classroom observation protocols to identify the characteristics of the lecture and instructional methods used by course instructors, to observe student and instructor behaviours, to evaluate the fidelity of certain implementations, and to understand classroom dynamics. This systematic review provides a synthesis and comparison of the features and dimensions of commonly used observation protocols in postsecondary (undergraduate or college) classrooms. This study identifies eight observation protocols, which are: Reformed Teaching Observation Protocol, Oregon Teacher Observation Protocol, VaNTH Observation System, Cooperative Learning Observation Protocol, Teaching Dimension Observation Protocol, Classroom Observation Protocol for the Undergraduate STEM, Classroom Interactive Engagement Observation Protocol, and Student Resistance and Instructional Practices. Based on 35 articles included in the full review, we present an overview description of each protocol. Further, we describe the strength and limitations of these protocols using deductive thematic and content analysis. Also, we evaluate these protocols by using the assessment triangle approach. The study advances the existing literature by providing usability details and suggestions to use each protocol. This review study also enhances the literature in science, technology, engineering and mathematics (STEM) education as the first study that evaluates all these observation protocols and provides a reference point for future researchers.