Online project-based learning (PjBL) is an increasingly popular teaching approach in higher education, especially in teacher education. Implementing online PjBL differs across subjects, bringing many benefits while posing challenges for educators and pre-service teachers. This systematic review aims to investigate the implementation, effectiveness and challenges of adopting PjBL in teacher education during the COVID-19 pandemic. The review provided a thorough overview of research on PjBL in teacher education during the COVID-19 pandemic, which was carried out using the systematic review methodology and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Several relevant articles from five different databases (Google Scholar, Mendeley, ScienceDirect, Scopus, and Taylor & Francis Online) were collected using the keywords "project-based learning" and "teacher education" along with their synonyms. A final list of 26 included articles to be reviewed in this study is produced after the titles and abstracts screening and full texts evaluation using inclusion and exclusion criteria. This systematic review reveals that PjBL has been applied in teaching various subjects in teacher education with different types of projects and assessment methods. More importantly, integrating PjBL in teaching has been proven to positively impact the development of pre-service teachers' knowledge, professional skills and learning attitudes. In addition, applying PjBL poses certain challenges for educators due to the requirements on teachers' and students' knowledge and skills as well as equipment and technology facilities. On the other hand, the COVID-19 pandemic, if viewed positively, contributes to boosting educators' motivation and facilitating the implementation of online PjBL. The study findings can be used as a reference for future PjBL research and contribute to the literature on PjBL in the context of teacher education.