Background: Recently, patient and public involvement (PPI) in research has gained significant attention, particularly within the United Kingdom. Although there has been a growing focus on the impact of PPI on research outcomes, there remains an important gap in understanding its effects on the individuals involved and the value they gain from their participation. Objective: This scoping review aims to critically examine how PPI benefits both people with lived experience and researchers, shedding light on the value of their involvement in shaping research. Methods: We searched MEDLINE, PsycINFO, EMBASE, Cochrane and Web of Science for full-text articles published in English after 1996. Grey literature searches reviewed policies from international research funders and patient organisations. Two reviewers independently carried out the abstract, title and full-text article screening stages. Data abstraction was performed by one reviewer and verified by a second reviewer. Thematic analysis synthesised the findings. Results: After searching 3024 citations, 107 published articles and nine unpublished resources were included in the review. Most of the studies were conducted in the United Kingdom in the last 10 years. Thematic analysis of the value of PPI revealed four main themes: (1) value from contributing to research, (2) importance of relationships, (3) attitudes and support for PPI and (4) emotional labour of involvement. Discussion: This scoping review reveals the significant contributions alongside systemic challenges of PPI in health research. Being valued was framed as an impact of PPI to both PPI advisors and researchers. It emphasises the importance of social capital in developing relationships between researchers and people with lived experience yet highlights barriers that can hinder effective collaboration. This can lead to experiential knowledge being undervalued as a crucial perspective to inform research. Despite people being chosen to take part on account of their knowledge, skills and lived experience, these resources were not always used to their full potential due to researchers' expectations and restrictive research and institutional processes. The review calls for coordinated efforts to improve how PPI is valued and practised beyond a process or method to ensure PPI is done thoughtfully and effectively.