K-12 pre-service teachers (PSTs, n=16) participated in a collaborative online teacher professional development program aimed at increasing their noticing and beliefs about embodied mathematical reasoning. Before and after the intervention, PSTs assessed the quality of students’ geometric reasoning as portrayed in videos of student speech and gestures, and completed a validated survey regarding teachers’ attitudes about gesture for learning and instruction. PSTs then participated in the collaborative embodied professional learning experiences, which included playing and then designing content for a motion-capture video game for improving students’ geometric reasoning and proof production through embodied interactions. Results from multimodal discourse analysis of video-prompted interviews with PSTs, epistemic network analysis, and the surveys reveal significant improvements in PSTs’ noticing, interpreting, and appreciating of embodied forms of mathematical ways of knowing, and improved attitudes about the role of gestures in learning and teaching. Implications are offered for developing teachers’ noticing skills and formative assessment practices that include students’ nonverbal ways of expressing mathematical reasoning, and for exploring embodied design activities to influence teachers’ attitudes and beliefs about the embodied nature of student thinking and learning.