This study aims to understand the relationships between authenticity and the constructs of theory of planned behaviour (TPB), namely, attitude, subjective norms, perceived behavioural control and behavioural intention, of pilgrims who participated in the Camino de Santiago walk in Spain. A survey involving 400 respondents was conducted and structural equation modelling was employed in analysing the data. Results revealed positive relationships between authenticity and attitude, subjective norms and perceived behavioural control. Attitude and subjective norms had a positive and significant relationship with behavioural intention, whereas perceived behavioural control showed an insignificant relationship with behavioural intention. Authenticity mediated by the TPB constructs positively influenced the behavioural intention of pilgrims. Findings of this study provide an improved understanding of how authenticity interacts with attitude, subjective norms and perceived behavioural control, thereby influencing the behavioural intention to walk the St. James Way. Thus, this study contributes to an improved insight into the impact of authenticity on pilgrims' behavioural intention.