Purchase engagement reflects the attitudes and behaviors of the customer in relation to their present and future purchases of the firm’s service (Kumar & Pansari, 2016). However, the concept of engagement in marketing has received less attention in business-to-business (B2B) contexts due to the complexity and heterogeneity in which the number of people involved in B2B buying decisions remains high than in consumer markets (Lilien, 2016). The challenges in developing B2B marketing theory also depends on the context and one such area that has been under-researched is the professional service firm (PSF) context (Casidy & Nyadzayo, 2017). According to Heirati et al. (2016, p.51) “…the field of B2B marketing contains limited research examining the role of PSFs' simultaneous collaboration with customers and suppliers under differing environmental conditions.” Also, there are calls for research to examine the drivers and outcomes of purchase engagement as it is a relatively nascent construct (Kumar & Pansari, 2016). Thus, this study sought to examine the drivers and outcomes of purchase engagement in B2B professional services. Using the structural equation modelling approach, the results from a survey of CEOs and/or owner-managers of small and medium-sized enterprises (SMEs) in Australia found that customization and loyalty to the account manager are two salient drivers of purchase engagement. In turn, purchase engagement is found to impact three outcomes namely consideration set size (CSZ), dependence and willingness to pay a premium price (WTP). An interesting finding in this study is the mediating role played by dependence as a mechanism through which engagement can impact CSZ and WTP. Practical and theoretical implications as well as research limitations and future research are discussed.