Abstract Background Health literacy refers to the skills needed to access, understand, and navigate health information and services. The Health Literacy Questionnaire (HLQ) is a widely used validated measure of health literacy capturing nine distinct domains. The HLQ-Parent is a recent adaption of the HLQ which has been designed to capture the nuanced health literacy skills required by primary care givers of children. Generating qualitative evidence of validity of such tools is an important element of the validation process as it captures understanding and interpretation of items which is not achievable by quantitative methods alone. Therefore, the purpose of this study was to generate qualitative evidence of the validity of the HLQ-Parent. Methods A qualitative study implementing the HLQ-Parent during face-to-face cognitive interviews with concurrent probing was conducted. Primary carers of children aged 16 or under living in England were recruited via voluntary organisations supporting families. Qualitative data analysis was conducted on the audio recordings in the form of text summaries. Parents’ chosen HLQ-Parent responses were compared to their narrative responses and coded by the researcher as match, no match or unclear. Parents’ narrative responses were also compared to the HLQ-Parent item intent descriptions and coded as concordant, discordant, or unclear. Results Overall, participants (n = 9, mean age 40 years, 88.9% female) narrative responses matched to their chosen HLQ-Parent response, while their narrative responses were concordant with the HLQ-Parent item intent descriptions. Two participants narratives did not match their responses for the item:’ I have enough information to help me deal with my child’s health’. Conclusions The qualitative data provided evidence that participants understood and answered the HLQ-Parent items as intended. Study results contribute validity evidence for the use of HLQ-Parent to measure parental health literacy. Key messages • This study contributes evidence to the validity of the HLQ-Parent. • Qualitative methods provide valuable insights that enhance the overall understanding of health literacy measurement tools.