Introduction  The number of foreign tourists and residents, including Muslims, requiring medical care in Japan is increasing. Little is known about the experiences of Japanese healthcare professionals (HCPs) who care for Muslim patients. This study aimed to describe healthcare professionals’ experiences and approaches to caring for Muslim patients as well as the HCPs’ knowledge and attitudes toward these patients. Methods  A key informant interview was conducted by interviewing healthcare professionals experienced in caring for international patients. Content analysis was used to analyze the interview data. Results  A total of 292 codes were extracted, and 18 subcategories were identified. Five categories were consequently identified. Four categories represented cultural competencies, including Islamic cultural and religious knowledge and how to deal with these issues, especially “halal (permissible) medicine” and Ramadan fasting; one category was related to the need for organizational support. The key informants demonstrated expert knowledge and skills in caring for Muslim patients. Our findings have implications for gathering more evidence on “halal medicine” and Ramadan in Japan, requiring the collective efforts of professional and academic organizations. Conclusion  The current study found that participants displayed culturally competent knowledge and attitudes toward Muslim patients. However, further efforts are necessary for developing evidence-based practice regarding the impact of Islamic religious practices on patients.