There are many affordances of integrating classroom-based global collaboration (CBGC) experiences into the K-12 STEM classroom, yet few opportunities for STEM preservice teachers (PST) to participate in these strategies during their teacher preparation program (TPP). We describe the experiences of 12 STEM PSTs enrolled in a CBGC-enhanced course in a TPP. PSTs participated in one limited communication CBGC (using mathematics content to make origami for a global audience), two sustained engaged CBGCs (with STEM PSTs and in-service graduate students at universities in Belarus and South Korea), and an individual capstone CBGC-infused project-based learning (PBL) project. Participating STEM PSTs reported positive outcomes for themselves as teachers in their 21st century skills development and increased pedagogical content knowledge. Participants also discussed potential benefits for their students in cultural understanding and open-mindedness. Implementation of each of these CBGCs in the STEM PST course, as well as STEM PST instructors’ reactions and thoughts, are discussed.