Background: Family caregivers of patients with cancer undergoing radiation therapy experience significant distress and challenges related to high symptom burden and complex care demands. This is particularly true for caregivers of patients with head and neck, esophageal, anal, rectal, and lung cancers, who are often receiving combined-modality treatment and may have tracheostomy tubes, gastrostomy tubes, or colostomies/ileostomies. This study aims to evaluate a simulation-based nursing intervention to provide information, support, and training to caregivers during radiation therapy. Methods: This randomized controlled trial will include a sample of 180 patients and their family caregivers. Caregivers assigned to the control group will receive usual care and an informational booklet from the National Cancer Institute (NCI). Those in the intervention group will receive usual care, the NCI booklet, and three meetings with a nurse interventionist during radiation treatment followed by a booster call two weeks posttreatment. Intervention sessions focus on themes consistent with the trajectory of radiation therapy: the patient experience/needs, the caregiver experience and dyad communication, and transition to survivorship. Outcomes are measured at baseline, end of treatment (T2), and 4 (T3) and 20 (T4) weeks posttreatment, with the primary outcome being caregiver anxiety at T4. Discussion: This trial is innovative in its use of simulation in a psychoeducational intervention for family caregivers. The intervention is administered at point-of-care and aimed at feasibility for integration into clinical practice. Patient quality of life and healthcare utilization measures will assess how providing support and training to the caregiver may impact patient outcomes. Trial registration: The trial was registered on 08/14/2019 at ClinicalTrials.gov (identifier NCT04055948).