Building health literacy in early childhood is essential for lifelong health and underpins children's learning and developmental trajectories. This study assessed the efficacy of the Little Aussie Bugs books, designed to enhance health literacy in Australian Early Childhood Education and Care (ECEC) centres. The books, featuring inclusive characters and key health literacy catchphrases, were distributed to >1200 early learning settings Australia-wide. Exploratory research design used online surveys (n = 110) and in-depth interviews with ECEC teacher participants (n = 8) to determine the compatibility of the books with ECEC contexts and practices to facilitate the delivery of health literacy education. The findings were conceptualized through a socioecological lens, using the process, person, and context over time model. Participants reported high overall satisfaction with the books, alongside increased confidence to deliver health literacy messages. Key advantages included the dialogic nature of the books, children's familiarity with catchphrases and characters, and children's understanding of otherwise abstract concepts, such as 'invisible germs'. However, these benefits were limited for less experienced educators who may not have understood the dialogic nature of the books, subsequently not utilizing them to their full capacity. These limitations indicate the need for further support to accompany the resources and maximize their impact. Further research is planned to inform the design of effective and appropriate professional learning to complement the resources, supporting educators to optimize their use of the books and promoting sustained delivery of health literacy messaging in ECEC settings.