The professional nurse advocate (PNA) programme aims to equip nurses with the skills to provide restorative clinical supervision, thereby enabling then to support other staff members. This article details a service evaluation to determine the effects of introducing the PNA programme in a mental health and learning disability NHS trust. Data on the PNA supervision sessions were collected using trust records, supervisee evaluations and a PNA experience survey questionnaire. The evaluation found that the PNA sessions primarily supported staff well-being and retention. The PNAs found the experience of delivering supervision rewarding, but they expressed challenges such as having insufficient time to facilitate sessions and a lack of ongoing development. This suggests that protected time for supervisees and PNAs needs to be provided, and that it may be beneficial to establish a continuing professional development programme for PNAs.