Abstract: Background: Ageism, defined as prejudice or discrimination based on age, is increasingly recognised as influencing health care experiences. However, its impact on older women’s access to preventive health services remains underexplored. Aim: This study explores how women aged ≥75 years perceive and experience ageism when accessing breast cancer screening in Australia. Methods: A secondary qualitative analysis was conducted using data from a 2022 Australia-wide study. Sixty women aged ≥75 years participated in in-depth interviews. Transcripts were analysed thematically using NVivo, informed by a theoretical lens of ageing and critical reflection on ageism. Results: Participants described changes in healthcare interactions associated with ageing, with ageism evident across multiple levels. At the individual level, women emphasised autonomy and self-determination. At the service level, they reported challenges related to communication, screening eligibility, and assumptions about ageing bodies. At the societal level, women described feeling part of an “invisible generation.” Experiences were shaped by generational differences, peer networks, and familiarity with technology. Both perceived and enacted ageism influenced engagement with screening, with increasing reliance on digital platforms identified as a barrier for some. Conclusions: Ageism operates across individual, healthcare, and societal contexts, shaping older women’s access to breast cancer screening. Addressing both implicit and explicit ageism is critical to improving engagement. Health promotion strategies should prioritise inclusive communication, reduce reliance on digital-only platforms, and recognise the diversity and agency of older women to support equitable access to preventive care.