Mothers are often responsible for vaccination decisions in the household. However, their confidence in certain vaccines such as Human Papillomavirus (HPV) vaccines is eroding in some countries. France is one of the countries with the lowest HPV vaccine uptake in Europe, with parents delaying or refusing the vaccine for their adolescent daughters due to safety- and effectiveness-related concerns. Although parental consent is required for vaccination, adolescents' involvement in HPV vaccination decision-making could improve vaccine uptake, with self-consent procedures already introduced in some countries. Adolescents' capacity to engage in decision-making is influenced by their maturity and autonomy in health. This study explored the role of maturity in decision-making around HPV vaccination in France through qualitative interviews with adolescent girls (n = 24) and their mothers (n = 21) and two focus groups with adolescent girls (n = 12). A codebook approach to thematic analysis revealed that adolescent girls' involvement in HPV decision-making is a process that evolved with maturity. As adolescents progressed towards maturity at different speeds, some expressed childlike traits such as impulsive decisions and others described more rational, reflective decision-making. Despite these differences, most adolescents in this study described a passive role in HPV vaccination decision-making, following their parents' lead. However, their expressed desire for information and involvement in discussions indicates that their lack of engagement may not only be due to a lack of maturity but also a result of mothers and doctors excluding them from getting involved. Furthermore, as health behaviours are shaped during adolescence, the influence of vaccine hesitant mothers on their daughters' own views and beliefs could be significant, together with exposure to regular controversies in the mainstream media. Individualised approaches to engage adolescents in decision-making around their own health are needed, for example through strengthening discussions and information around HPV vaccination with parents and doctors.