Thailand is now a medical center in Asia. There has been an increase in the number of foreign patients receiving medical services in Thailand. The employees in the healthcare industry, like the registered nurse, are the center of the relationship with that service. The vital learning promotion course for these registered nurses dealing with patients of various nationalities is cultural competence promotion. With the nature of the learning style of the registered nurse, they need more flexibility and respond to their learning nature. Ultimately, the enhancement of cultural competency learning still needs to be achieved. Therefore, this research study aimed to: 1) develop a self-directed learning program in the workplace to promote cultural competence for registered nurses in international hospitals and 2) study the effect of implementing a self-directed workplace learning program to promote cultural competency. The researcher adopted a Research and Development methodology divided into two phases. The first phase is to develop a self-directed workplace learning program to enhance cultural competency. The second phase is to study the effect of implementing a self-directed learning program. The findings revealed that: 1) a draft of a self-directed workplace learning program to enhance cultural competence consisting of concepts and principles, the primary goal of the program, the guideline for promoting cultural competence learning based on the idea of self-directed workplace learning, the learning program, the learning facilitators of the program, the learning spaces are locations or areas within an organization, the international hospital's networks and the learning resources include information sources from diverse places. Plus, 2) registered nurses had better levels of cultural competency learning in attitudes, knowledge, and skills than before participating in the program trial and had improved scores in all areas.