Purpose: To assess whether the COVID-19 pandemic delayed breast cancer diagnosis in Taiwan, an Asian country with a low COVID-19 incidence. Methods: The monthly volume of breast biopsies and breast cancers during the COVID-19 pandemic (during January 21 and July 31, 2020) was compared to the same period in 2019 (pre-COVID-19). Results: Taiwan recorded a lower COVID-19 incidence rate (20.2 cases per million population) than other Asian countries. The screen-detected lesions accounted for 55% and 36% of 2019 and 2020 total biopsied lesions, respectively. Total breast biopsy, mammography-guided, and ultrasound-guided biopsies decreased by 17%, 23%, and 14%, respectively, from pre-COVID-19 to COVID-19. Monthly differences were significant in total biopsy (p=0.03), mammography-guided biopsy (p=0.04), and a benign pathology result after breast biopsy (p<0.01). Nearly 46% decline was noted in the biopsy results of non-invasive breast cancer in 2020. The number of total breast cancers and early breast cancers (stages 0 and 1) decreased by 10% and 38%, respectively, during pandemic. Individuals with early breast cancer accounted for 71% and 49% of the total diagnosed breast cancer in the pre-COVID-19 and COVID-19 periods, respectively (p<0.001). Conclusion: The pandemic significantly delayed early breast cancer detection in Taiwan despite low COVID-19 incidence. Clinical Trial Registration: ClinicalTrials.gov, NCT04750018.