The aim of the study was to examine the effects of rubric co-creation on peer feedback. From a social constructivist perspective, rubric co-creation might have the ability to promote the quality of feedback messages, interactivities within feedback processes, and uptake of feedback information in a peer-based collaborative setting of higher education. Two groups of English Language Studies majors (N = 57) from a Chinese university were recruited. In a writing class enacting peer feedback, the experimental group participated in the co-creation of rubrics whereas the control group accepted and used the co-created rubrics. Results showed that rubric co-creation had significantly positive effects on students' use of criteria and the production of meaningful feedback messages instead of feedback writing styles. Regarding interaction patterns, the experimental group established active and bi-directional dialogic communication between peer learners. For uptake of feedback, the experimental group made significantly more critical application of feedback messages compared to the control group. The paper has implications for the enactment of rubric co-creation in peer-based learning and the promotion of learner agency in dialogic feedback interactions.