Abstract Background Pharmacists are being increasingly employed as part of general practice teams globally, and their input has been associated with several clinical and economic benefits. However, there is a paucity of research focussing on general practitioners’ (GPs’) perceptions of pharmacist integration into practices in countries where this novel role for pharmacists is yet to become commonplace. Objective To explore GPs’ perceptions of integrating pharmacists into general practices and to identify the behavioural determinants of GPs integrating pharmacists into practices. Methods Semistructured interviews were conducted with GPs practising in Ireland, who were sampled using a combination of purposive, convenience, and snowball sampling. Interviews were audio-recorded and transcribed verbatim, which then were analysed using conventional content analysis and directed content analysis employing the Theoretical Domains Framework (TDF). Results Seventeen GPs were interviewed between November 2021 and February 2022. Seven TDF domains were identified as predominant in influencing GPs’ perceptions of pharmacist integration into general practices. These perceptions were mostly positive, especially regarding patient outcomes, cost savings, and improving access to care. However, there were concerns about funding the role, affecting others’ workloads, and pharmacists’ training needs to work in practices. Conclusion This study’s theory-informed insight provides a deeper understanding of GPs’ perceptions of pharmacists working in general practice and behaviours which can be targeted to help optimize integration. These findings should be utilized in future service development to preempt and address GPs’ concerns ahead of pharmacist integration, as well as to inform the development of general practice-based pharmacist roles going forward. Lay Summary This interview study focusses on, for the first time, general practitioners’ (GPs’) perceptions of pharmacist integration into general practices outside of a private practice setting. Pharmacists working in general practices have demonstrated several benefits for patients, GPs, practices, and for wider society. However, pharmacist roles in general practices have thus far been confined to a small number of countries; little is known about the perceptions of GPs who have not previously worked alongside a pharmacist in general practice regarding pharmacist integration in this setting. GPs interviewed in this study were broadly optimistic about aspects of pharmacists working in practices and potential outputs. However, GPs had concerns about pharmacists’ impact on others’ roles and workloads, funding, and training pharmacists to perform roles in this setting. This study therefore provides a useful insight into GPs’ perceptions on the subject so that their views, concerns, and ideas can be anticipated and taken on board in advance of trying to integrate pharmacists into practices.