We sought to understand the objectives, targeted populations, therapeutic elements, and delivery characteristics of patient portal interventions. Following Arksey and O-Malley's methodological framework, we conducted a scoping review of manuscripts published through June 2022 by hand and systematically searching PubMed, PSYCHInfo, Embase, and Web of Science. The search yielded 5403 manuscripts; 248 were selected for full-text review; 81 met the eligibility criteria for examining outcomes of a patient portal intervention. The 81 articles described: trials involving comparison groups (n = 37; 45.7%), quality improvement initiatives (n = 15; 18.5%), pilot studies (n = 7; 8.6%), and single-arm studies (n = 22; 27.2%). Studies were conducted in primary care (n = 33, 40.7%), specialty outpatient (n = 24, 29.6%), or inpatient settings (n = 4, 4.9%)-or they were deployed system wide (n = 9, 11.1%). Interventions targeted specific health conditions (n = 35, 43.2%), promoted preventive services (n = 19, 23.5%), or addressed communication (n = 19, 23.4%); few specifically sought to improve the patient experience (n = 3, 3.7%). About half of the studies (n = 40, 49.4%) relied on human involvement, and about half involved personalized (vs exclusively standardized) elements (n = 42, 51.8%). Interventions commonly collected patient-reported information (n = 36, 44.4%), provided education (n = 35, 43.2%), or deployed preventive service reminders (n = 14, 17.3%). This scoping review finds that most patient portal interventions have delivered education or facilitated collection of patient-reported information. Few interventions have involved pragmatic designs or been deployed system wide. The patient portal is an important tool in real-world efforts to more effectively support patients, but interventions to date rely largely on evidence from consented participants rather than pragmatically implemented systems-level initiatives.