<p>Career development theories can help practitioners to support their clients’ career development, yet evidence suggests that they are not well used in practice. This study explores career practitioners’ perceptions of the value that career development theories can add in guidance. Data were gathered through semi-structured interviews with thirty UK career practitioners exploring their perceptions of the benefits of theory-driven practice and were analysed with a reflexive thematic analysis. Three themes were developed: theories add value through boosting the confidence of client and practitioner, through deepening the understanding of client and practitioner, and through directly and indirectly improving career guidance conversations.</p>