Image-generating AI provides diverse sources for ideation in fashion design education. This study explores how collaborative fashion ideation with AI influences image thinking and creativity in a changing media environment. The research method employed design workshops and in-depth interviews with 10 students. The findings reveal that collaborative fashion ideation with AI influences image thinking through visual expansion, exploration of its applicability in fashion, and identifying and lack of sociocultural understanding and identity in idea combination. Collaborative fashion ideation with AI emphasizes creative properties, such as originality, fluency, and flexibility. The results of design workshops, evaluated by experts, indicate higher originality and novelty compared to the control group. The results imply that various factors, such as individual aesthetic presence and the identity of fashion brands, contribute to fashion ideation. Therefore, in collaborative ideation with AI, rather than relying solely on AI tools, it is essential to perceive and approach them as auxiliary tools. This study contributes to elucidating students' image thinking and creative attributes in fashion ideation, highlighting the impact of collaborative ideation with AI.