Breast cancer is one of the leading causes of death and disability globally. Although mammogram has been identified as a significant breast screening tool in the United States, researchers have indicated that African-born women in the United States are diagnosed with advanced stages of breast cancer because of underutilization of mammogram from diverse reasons. The purpose of this quantitative study was to determine the association of demographic factors, breast cancer knowledge, health beliefs, and the utilization of mammogram among Nigerian women, 40 years and older in the United States (N=200). The study was guided by the health belief model and questionnaire was the data collection instrument used. Logistic regression analysis revealed that demographic variables, specifically age and length of residency in the United States have statistically significant effect on the odds of utilization of mammogram among the Nigerian women in the U.S. at p < 0.05. Also, according to the study results, breast cancer knowledge has a statistically significant effect on the utilization of mammogram at p <0.05. Additionally, health beliefs regarding breast cancer have significant effect on utilization of mammogram among Nigerian women 40 years and older in the U.S at p <0.05. The study findings will help in developing breast health programs for immigrant women, especially Nigerians in the U.S. to make informed decisions about timely utilization of mammographic services. Furthermore, the outcome of this study could enhance research, enlighten the health providers, and policymakers to develop culture sensitive preventive breast health programs that are appropriate to diverse women populations in the United States.