Background Despite the extensive use of mixed methods across health sciences, there has been a limited discussion about the methodological rigour and quality in mixed methods research (MMR). Although the empirical and methodological literature about mixed methods is increasing, there are few practical examples of the implementation of rigour criteria.

Aim To discuss and illustrate the application of ‘legitimation criteria’ to the design and conduct of a sequential exploratory MMR study of nurse educators’ challenges when teaching undergraduate students.

Discussion The legitimation criteria can establish philosophical and methodological validity and rigour in MMR. MMR is complex and daunting, so maintaining rigour is crucial in ensuring the conclusions drawn are plausible and researchers, practitioners and policymakers use them to guide research and practice.

Conclusion The legitimation criteria are specific to MMR and are useful in improving the conduct and execution of studies. They enable researchers to maintain quality throughout their studies, from the development of a research question to the generation of conclusions.

Implications for practice This illustration of the legitimation criteria for the design and conduct of MMR will guide researchers in establishing rigour and lessen the threats to their studies’ validity.