PurposeBy exploiting the relationships between Six Sigma and quality management systems (QMS) based on the ISO 9001 standard, this paper proposes a set of guidelines to combine and integrate both approaches in a systematic way. The guidelines are organised into integration topics, and each one is linked to the clauses of the ISO 9001 standard they refer to.Design/methodology/approachBased on the literature review, Six Sigma and QMS based on the ISO 9001 standard are thoroughly discussed and compared and beneficial synergies between them are identified. Based on this study, and to take advantage of the compatibilities and logical linkages between both approaches, guidelines for the integration of Six Sigma with the ISO 9001 requirements are developed.FindingsBenefits resulting from the integration of Six Sigma with a QMS based on the ISO 9001 standard are mutual. The integration guidelines proposed in this paper provide a framework to unify process management practices, enhance the effectiveness of continual improvement efforts, facilitate the identification, evaluation and selection of Six Sigma projects, align the quality objectives defined for the QMS with Six Sigma project goals, establish relationships between the roles of a Six Sigma program and those inherent to an ISO 9001 QMS, and demonstrate how internal quality audits and management review benefit from a Six Sigma program.Research limitations/implicationsThe integration models and guidelines herein proposed can be further expanded to include other relevant normative references, particularly environmental management systems (ISO 14001) and safety and health management systems (OHSAS 18001).Originality/valueThe set of guidelines proposed in this paper is original and will be of practical value to the increasing number of organisations adopting a process‐model for the ISO 9001 standard, that seek to incorporate Six Sigma principles, practices, methods and tools within their QMS. The guidelines cover a wide spectrum of relevant activities that usually take place in the context of both initiatives. In addition, because each guideline is accompanied by the identification of the applicable clauses of ISO 9001, they provide a useful framework to develop, implement, maintain, and improve a QMS in parallel with a Six Sigma program.