We sought to understand the factors influencing the implementation of a primary care intervention to improve post-discharge care following acute kidney injury (AKI). Qualitative study using semi-structured interviews and thematic analysis. General practices in one Clinical Commissioning Group area in England. A total of 18 healthcare staff took part in interviews. Participants were practice pharmacists, general practitioners, practice managers and administrators involved in implementing the intervention. We identified three main factors influencing implementation: differentiation of the new intervention from other practice work; development of skill mix and communication across organisations. Overall, post-AKI processes of care were deemed straightforward to embed into existing practice. However, it was also important to separate the intervention from other work in general practice. Dedicating staff time to proactively identify AKI on discharge summaries and to coordinate the provision of care enabled implementation of the intervention. The post-AKI intervention provided an opportunity for practice pharmacists to expand their primary care role. Working in a new setting also brought challenges; time to develop trusting relationships including an understanding of boundaries of clinical expertise influenced pharmacists' roles. Unclear and inconsistent information on discharge summaries contributed to concerns about additional work in primary care. The research highlights challenges around post-discharge management in the primary care context. Coordination and communication were key factors for improving follow-up care following AKI. Further consideration is required to understand patient experiences of the interface between secondary and primary care. The issues pertaining to discharge care following AKI are relevant to practitioners and commissioners as they work to improve transitions of care for vulnerable patient populations. © Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.