IntroductionPatient adherence to adjuvant endocrine therapy (AET) after a diagnosis of hormone-sensitive breast cancer is poor. Previous interventions have failed to produce changes in adherence, address patient preferences or include theoretically informed and evidence-based components. Therefore, we iteratively developed a patient-centred, evidence-based, small-group, videoconference intervention to improve adherence and symptom management as well as reduce distress for patients taking AET after breast cancer (Symptom-Targeted Randomised Intervention for Distress and Adherence to Adjuvant Endocrine Therapy, STRIDE).Methods and analysisThe current study is a non-blinded, randomised, controlled, feasibility trial of STRIDE compared with a medication monitoring control group. The primary objective is to examine the feasibility and acceptability of STRIDE, while secondary objectives are to assess changes in objective and subjective adherence, symptom distress and satisfaction with AET. Patients will be recruited from the Massachusetts General Hospital Cancer Center in Boston, Massachusetts. The total number of patients accrued will be 75, with ≥60 patients completing the study. All patients will store their AET in an electronic pill bottle for objective adherence monitoring. Patients randomly assigned to the STRIDE intervention will receive 6 weekly 1-hour sessions, in small groups of two, delivered via videoconferencing by a trained mental health professional. Patients assigned to the control group will store their medication in the electronic pill bottle and receive follow-up oncology care as usual. All participants will complete self-report psychosocial measures at baseline, 12 weeks and 24 weeks postbaseline.Ethics and disseminationThe study is funded by the National Cancer Institute of the National Institutes of Health and is approved by the Dana-Farber/Harvard Cancer Center Institutional Review Board (Protocol #18–603, V.1.2, first approval date 1 February 2019). The study will be reported in accordance with the Consolidated Standards of Reporting Trials statement for non-pharmacological trials. Results will be published in peer-reviewed academic journals, presented at scientific meetings and disseminated to patient organisations and media outlets.Trial registration numberNCT03837496; Pre-results.