Abstract Background Sentinel lymph node biopsy (SLNB) underuse has been reported for skin cancers; however, actual performance rates have not been compared. The objective of this study was to investigate the SLNB performance rate in skin cancers covered by health insurance in Japan and compare it with that in breast cancer. Methods This was a retrospective study of the SLNB performance rate in SLNB‐eligible patients with breast or skin cancer from 2018 to 2019, utilizing a database linked to the Hospital‐Based Cancer Registry and Diagnosis Procedure Combination survey. Demographic and tumor characteristics were analyzed using logistic regression. Results A total of 71,652 patients were included in this study. SLNB was performed in 86.4% (57,904/67,036) of the patients with breast cancer, 44.7% (694/1552) with melanomas, 3.1% (89/2849) with squamous cell carcinomas (SCCs), and 13.5% (29/215) with Merkel cell carcinomas (MCCs). The performance rate of SLNB was significantly lower for skin cancers than for breast cancers (odds ratio [OR], 0.03; p