This paper examines Chinese (n = 11) and Spanish (n = 11) student teachers' learning-to-teach experiences during the teaching practicum or placement period through the lenses of transformative learning theory and third space construct. We traced student teachers' transformative learning experiences through observation, interviews, reflective journaling, and metaphoric identity narratives. Five major themes emerged related to the participants' professional learning experiences: (1) the disorienting dilemmas, (2) reflections and explorations of assumptions, (3) gaining confidence in a new role, (4) behaviour changes, and (5) integration of new perspectives. Moreover, third space helped the participants negotiate a series of binaries undesirable in teacher education, such as episteme and phronesis, stability, and evolution of their professional identities. This paper contributes to a fine-grained account of Chinese and Spanish student teachers' professional learning experiences in different sociocultural contexts. Implications for fostering Eastern-Western dialogues on teachers' transformative learning experiences and creating third space (hybridity and boundary-crossing) in teacher education are discussed.