Aim: This systematic review aims to qualitatively synthesize available evidence on the effect of the smear layer (SL) on the adhesion of bioceramic root canal sealers to dentin. Methods: An advanced literature search was conducted in PubMed and Cochrane, targeting in vitro studies on human teeth published between January 2013 and January 2024, in English. Results: The search yielded 479 articles where 16 studies met the inclusion criteria and were included. Data were collected according to the number of teeth studied, canal preparation, smear layer removal methods, adhesion tests, and sealer types. The review found no consensus on the SL's impact on the adhesion and sealing ability of bioceramic sealers. While MTA-based sealers showed improved adhesion due to the SL's role in forming an interfacial layer, calcium silicate-based sealers either experienced reduced adhesion or were unaffected by the SL. Conclusion: The effect of the smear layer on bioceramic sealer adhesion remains unclear, with variations depending on sealer type, smear layer properties, and irrigants used. For MTA-based sealers, the smear layer plays a significant role in enhancing adhesion. Further research is needed to clarify these interactions.