Rationale and Aims Scholars have progressively promoted shared decision making (SDM) as an optimal model of treatment decision making in clinical practice. Nevertheless, it is unclear whether health care professionals (a) understand SDM well, (b) believe that SDM is helpful in their daily practice, and (c) are willing to practice SDM during their daily activities. These are crucial research topics; however, such research is still limited. The aim of this study was to apply the knowledge‐attitude‐behavior (KAB) model to probe health care professionals' perceptions of SDM. Methods A questionnaire was delivered to health care professionals working in various hospitals in southern Taiwan from 9 November 2018 to 8 January 2019. In addition to KAB constructs, this study explored the barriers to SDM practice and willingness to practice SDM among health care professionals. Predictive variables were subjected to multiple linear regression analysis to investigate health care professionals' views of SDM. Results Valid respondents numbered 400, including physicians, pharmacists, nurses, and other health care professionals. The characteristics of these health care professionals significantly affected the mean scores of the KAB model. A correlation analyses indicated that the KAB constructs were positively correlated with each other. The top three barriers reported were lack of time (57.50%), lack of knowledge (38.25%), and difficulty of developing patient decision aids (37.75%). Respondents who were willing to practice SDM opined that SDM can provide the best health care for patients (81.62%), can maintain and improve individual clinical expertise (77.38%), and can meet patient and social expectations (48.40%). Conclusions Continuous emphasis on education regarding SDM and continuous promotion of a positive attitude of SDM acceptance can influence the behaviour of practicing SDM among health care professionals. Further study is required to assess the SDM practices of various health care professionals in different settings.