Background In a growing number of countries worldwide, clinicians are sharing mental health notes, including psychiatry and psychotherapy notes, with patients. Objective The aim of this study is to solicit the views of experts on provider policies and patient and clinician training or guidance in relation to open notes in mental health care. Methods In August 2020, we conducted a web-based survey of international experts on the practice of sharing mental health notes. Experts were identified as informaticians, clinicians, chief medical information officers, patients, and patient advocates who have extensive research knowledge about or experience of providing access to or having access to mental health notes. This study undertook a qualitative descriptive analysis of experts’ written responses and opinions (comments) to open-ended questions on training clinicians, patient guidance, and suggested policy regulations. Results A total of 70 of 92 (76%) experts from 6 countries responded. We identified four major themes related to opening mental health notes to patients: the need for clarity about provider policies on exemptions, providing patients with basic information about open notes, clinician training in writing mental health notes, and managing patient-clinician disagreement about mental health notes. Conclusions This study provides timely information on policy and training recommendations derived from a wide range of international experts on how to prepare clinicians and patients for open notes in mental health. The results of this study point to the need for further refinement of exemption policies in relation to sharing mental health notes, guidance for patients, and curricular changes for students and clinicians as well as improvements aimed at enhancing patient and clinician-friendly portal design.