While an expanding body of evidence emerged recommending that teachers stay engaged with the professional learning communities (PLCs) to enhance career development, scant attention has been given to exploring the relationship between teacher agency and their professional commitment to PLCs. To bridge this gap, the current study aims to uncover teachers' views on community practices and the enabling and restraining factors that influenced their enactment of professional agency in a sample of 10 Chinese university language teachers. Thematic analysis was applied to scrutinize the data collected from semi-structured interviews, community observation, reflective diary, and discussion minutes in PLCs. The results of teachers' reported experience showed the significant effect of PLCs in constructing language teachers' professional developmental trajectories, facilitated by the reciprocal relations between teacher agency and commitment. An inquiry into teacher engagement reported that the participants proactively exercised their agency through the dynamic interplay of teacher identity, professional learning knowledge, teacher trust, and school culture in the community context. In addition, teacher commitment to PLCs was shaped by community identity, learning demands, exercised efforts, and teacher turnover. Some important theoretical and practical implications of this study were discussed.