Abstract Background Improving access to general practitioner (GP) services is seen as a way to enhance patients’ experiences. England introduced the national extended access scheme to provide routine and urgent GP appointments outside core hours. However, little is known about how this initiative affects patient experience, especially in terms of efficiency and equity. This study aimed to estimate the differential effects of extended access appointments on patient-reported satisfaction, focusing on different service delivery types to assess efficiency and on patient characteristics to evaluate equity of access. Methods A retrospective observational study was conducted using data from the English GP Patient Survey (GPPS) (2018 and 2019), linked with data on extended access from NHS records (March 2017 and March 2018). Regression models were used to examine associations between different types of extended access service delivery and patient experience measures (overall experience with GP, satisfaction with appointment time, overall satisfaction with making an appointment, and frequency of seeing or speaking to a preferred GP). Main heterogeneous analyses tested whether effects varied by patient age and employment status. Additional heterogeneous analyses assessed whether the effects differed in patient awareness of services and service providers (GP or GP group where practices collaborate). Results The analyses did not identify significant linear associations between extended access services and patient experience measures. However, some evidence suggested that the frequency of seeing or speaking to a preferred GP (a measure of continuity of care) was negatively associated with extended access services, although not linearly. The effect of extended access did not differ by age, but a small positive effect was observed on satisfaction with appointment times for patients in full-time employment. The study also found that greater cooperation between GPs positively impacted patient experience but might compromise continuity of care. Conclusions The national extended access scheme had a positive effect on improving satisfaction with appointment times for patients in full-time work, but the effect was not seen across the whole population. The provision of extended access services by GPs at scale may provide additional capacity and choice of care for patients, but care continuity could be threatened.