Background: Peer teaching is a student-centered learning method that enhances learning effectiveness through shared understanding and interaction. Cognitive congruence and social congruence are key mechanisms underlying the effectiveness of peer-assisted learning. Objective: This study aimed to explore students’ perceptions of cognitive congruence and social congruence through peer teaching implemented in balanced nutrition training. Methods: A quasi-experimental study with a qualitative approach was conducted among 30 undergraduate students at Nusa Cendana University. Participants were divided into two groups: students taught by peer tutors with prior nutrition knowledge and students taught by peer tutors without prior knowledge. Data were collected through Focus Group Discussions and analyzed thematically. Results: Peer teaching facilitated cognitive congruence through the use of simple, familiar language and shared knowledge frameworks. Social congruence emerged in the form of a comfortable learning atmosphere, empathetic tutor–tutee relationships, and open communication. Both tutor groups were perceived as effective, although tutors with prior knowledge delivered material more systematically. Conclusion: Peer teaching positively influences cognitive and social congruence and is an effective approach for balanced nutrition education among university students.