This project investigated how Wikipedia can be integrated into flipped learning in higher education through the project-based learning approach. It proposed a flipped learning model where Wikipedia was involved in creating a collaborative learning environment. Two groups of students participated in the research and were asked to complete group projects of creating Wikipedia entries, one of which learned in the flipped classroom, the other in the conventional classroom. An online collaborative learning platform, GMoodle, was developed to provide an interactive learning environment for the participants' learning with Wikipedia. The results showed that learning with Wikipedia in the flipped classroom was more effective than learning with Wikipedia in the conventional classroom. The participants in the flipped group created more versions of Wikipedia entries. The flipped learning environment provided the students with more in-class collaboration and interaction opportunities, leading to more time and space for active learning.