Introduction Clinical practice guidelines (CPGs) and consensus statements (CSs) are being promoted to provide high-quality healthcare guidance. This systematic review has assessed the breast cancer (BC) screening CPGs and CSs quality and reporting. Methods A search of bibliographic databases (MEDLINE, Embase, Web of Science, Scopus and CDSR), 12 guideline databases and 51 professional society websites was performed without language restrictions from January 2017 to June 2020, following prospective registration (Prospero no.: CRD42020203807). AGREE II (% of maximum score) and RIGHT (% of total 35 items) appraised quality and reporting individually, extracting data in duplicate; reviewer agreement was 98% and 93%, respectively. Results Forty guidances with median overall quality and reporting 51% (interquartile range [IQR] 39-63) and 48% (IQR 35-65), respectively. Twenty-two (55%) and 20 (50%) did not reach the minimum standards (scores <50%). The guidances that deployed systematic reviews had better quality (74.2% vs. 46.9%; p = 0.001) and reporting (80.5% vs. 42.6%; p = 0.001). Guidances reporting a tool referral scored better (AGREE II: 72.8% vs. 43.1%, p = 0.002; RIGHT: 75.0% vs. 46.9%, p = 0.004). Conclusion BC screening CPGs and CSs suffered poor quality and reporting. More than half did not reach the minimum standards. They would improve if systematic reviews were used to underpin the recommendations made.