Background and aim: Patient and public involvement (PPI) has potential to enhance health‐care research and is increasingly an expectation, particularly for many funding bodies. However, PPI can be tokenistic, which may limit this potential. Furthermore, few studies report PPI processes and impact, particularly in doctoral research studies, which are seldom reported in peer‐reviewed papers. The aim of this paper was to explore the impact of PPI on two health‐related doctoral research studies and identify how PPI could be used meaningfully at this level. Method: The PPI processes included (a) involvement of two 'Research Buddies' who informed the research design and ensured implementation of a booklet intervention was feasible for family carers, (b) data analysis workshops with 'Research Buddies' to identify emerging themes from practitioner interviews, (c) public and stakeholder involvement who informed data collection tool design, and the design of an intervention to help people with obesity who attend weight loss groups. Findings: The application of PPI enhanced both doctoral studies by assisting data analysis; problem solving and improving recruitment rates; improving the usability and appeal of data collection tools and interventions; and developing implementation strategies. Patient and public involvement was considered a rewarding experience for both researchers and PPI contributors. Conclusion: This paper demonstrates the value of PPI in doctoral research in relation to its impact on research processes, researchers and contributors. We also present recommendations on how PPI could be incorporated into future doctoral research, including resources required, planning PPI processes and involving PPI contributors in all stages of research.