Objective: During the care process, family members who provide care for a patient with cancer are confronted with changes in their family dynamics. The purpose of this study was to evaluate the family peace of caregivers of patient with cancer and the associated factors. Methods: A cross-sectional study was conducted in a single center. The sample of the study included caregivers who were family members of patients with cancer. Data were collected with Caregiver and Patient Information Forms, General Self-Efficacy Scale, Family Peace Scale, Self-Care Behaviors Scale, and MD Anderson Symptom Inventory. Results: It was found that the mean age of the caregivers was 50.20 ± 0.71 years, 64.1% were female, 78.7% were married. The mean score of the caregivers on the total family peace scale was above the average value with 46 ± 0.75 out of 75 points. The caregivers’ level of family peace increases as their scores on the scale increase. The family peace of caregivers who were widowed or divorced, were self-employed, had less income than their expenses, had a chronic disease, reported that their health was affected, had low self-efficacy was worse than that of others. The family peace of caregivers of patients who had gynecological cancer and had a good income was better ( P < 0.05). The self-efficacy level of the caregivers and the symptoms of the patient with cancer were significant predictors of family peace ( P < 0.001). Conclusions: Family peace of caregivers was affected by the type of cancer, symptom burden, self-care behaviors of the patient, and caregivers’ income status, chronic disease, marital status, and self-efficacy. Physicians and nurses, who are in close contact with caregivers of cancer patients, should be aware of the issue, professionals should assess the family environment of the caregivers of patient with cancer and counseling should be provided if deemed necessary.