This study develops existing theoretical and empirical understanding of the relationship between professionals and their clients situated in professional service firms (PSFs). It does so drawing on a career lens and regarding careers as contested and triadic in nature. In particular, it examines how the influence of clients is constructed during the promotion to partnership in seven law firms. The study identifies three forms of influence which were presented in participants’ talk: decision-makers, boundary creators and promotional referents. They all describe the client as being central to organisational processes underpinning promotion decisions in PSFs. Based on our findings we propose several implications. First, we extend existing understandings of the relationship between professionals and clients, focusing on the concept of client capture by analysing how and where client capture takes place. Second, we develop a triadic approach to careers, introducing the role of the client, and show how clients influence career processes and practices in PSFs.