This study investigated the impact of online peer and teacher feedback on students' self-regulated learning and analysed students' perceptions of online peer feedback on self-regulated learning development. The study employed a mixed method by collecting quantitative and qualitative data together. The study comprised 45 pre-service English as a Foreign Language (EFL) teachers as participants, and they were assigned to experimental and control groups. While online peer feedback was used in the experimental group, online control group was employed in the control group. Padlet online environment was used for online peer feedback and online teacher feedback. The quantitative results showed that the experimental group students had higher self-regulated learning levels than those in the control group. The qualitative results revealed that online peer feedback can have a positive impact on students' self-regulated learning.