The purpose of the study was to examine the effects of the relationship among protean career attitude, career adaptability, career satisfaction, and professional commitment of Taiwanese workers. We also investigated the mediating effect of career adaptability between protean career attitude and career satisfaction as well as between protean career attitude and professional commitment. Online survey was utilized to collect information from the Taiwanese workers. A total of 471 copies of questionnaires were collected in 4 months. The regression analysis results revealed that (1) protean career attitude predicted career adaptability, career satisfaction, and professional commitment; (2) Career adaptability mediated the relations between protean career attitude and career satisfaction or professional commitment. According to the findings of the research, we proposed theoretical and practical implications, research limitations, and recommendations to future research directions and practical management implications.