Background When researching female patients with breast or ovarian neoplasms, our research will sensitize oncologists to the prevalence of biliary tract cancers such that early cancers are not overlooked. Depending on different inherited, environmental, and iatrogenic risk factors, patients diagnosed with cancer have a risk of harboring another de novo malignancy. The additional primary identification of late has increased mainly due to progress in both diagnosis and treatment modalities, improvement in life expectancy, and understanding. Methods This is a descriptive study of retrospectively collected data from health records over 15 months, of patients who had biliary tract cancer and incidentally detected coexisting second non-biliary malignancy, from July 2018 to September 2019 at a tertiary care hospital. Details such as age, sex, smoking history, family history, occupation, body mass index (BMI), the organ involved, levels of tumor markers, treatment, and outcome were recorded. Results Six consecutive patients with biliary tract cancer presented during this duration and incidentally detected the second primary was ovarian cancer in three (50%) patients, breast carcinoma in two (33%) patients, and urinary bladder carcinoma in the remaining one patient (17%). The median age at diagnosis was 52.5 years with a range of 40-65 years. All patients were females (100%), non-smokers, homemaker, and without any history of cancer in family members. Only two patients who had a resectable disease were alive at one year\'s follow-up. Conclusion The mechanisms of carcinogenesis in multiple primary malignancies are mainly genetic, epigenetics, and immunological. Prognosis, as well as the intent of treatment, depends on the respective stages of the two malignancies. In our study, most of the patients were in an advanced stage that demanded palliative care.