As large communities, the efficiency and effectiveness of waste management on university campuses are of concern. This study aims to verify the variable relationship, influence path, and regulating factors of college students’ attitudes and behavior toward waste separation. A questionnaire survey was conducted at Henan Institute of Science and Technology, China, with 1300 respondents, among which 1213 questionnaires were valid. The SPSS software v23.0 was used to carry out the statistical analysis of the collected data by applying multiple analyses. The results showed that (i) females outperform males across attitudes and internal and external contextual factors, (ii) freshmen showed more positive waste separation behaviors, while upper-year students’ behaviors were more susceptible to contextual factors, (iii) college students’ attitudes, especially the knowledge factor, have a significant positive influence on behaviors, and (iv) the external contextual factors, as moderating variables, have a significant difference in the impact amplitude at different levels when attitudes affect behaviors. Our findings supplement the limited information available on the potential implications of applying the ABC model in exploring the factors influencing waste separation behaviors among college students. The provided insights can support college students, university administrators, policymakers, and government departments in more effectively optimizing, designing, and managing waste systems on campuses.