More than 400,000 prisoners across India are imprisoned without conviction and are awaiting criminal trials. A significant portion of these undertrial prisoners face severe social and economic hardships, making it difficult for them to hire competent legal services. Despite these conditions, only a few undertrial prisoners opt for state-sponsored legal aid services. Existing studies have found several concerns with state-sponsored legal aid, including a lack of accountability and inefficient service. However, there is limited research on how these issues and other factors limit the access and utilisation of legal aid services. This study investigates the reasons for the low uptake of legal aid services among prisoners in Jharkhand, India, through a qualitative methodology based on semi-structured interviews of 20 undertrial prisoners, 4 legal aid lawyers and 5 private lawyers. The interviews were thematically analysed across five dimensions of accessibility adapted from Levesque et al.’ (Int J Equity Health 12(1):18, 2013) theory of access to healthcare—approachability and ability to perceive, acceptability and ability to seek, availability and ability to reach, affordability and ability to pay and appropriateness and ability to engage. The study finds that the accessibility of legal aid services in Jharkhand is restricted across all five dimensions of accessibility, resulting in a low uptake of legal aid services by undertrial prisoners in Jharkhand. Participants highlight several reasons for low utilisation of service, including difficulty in reaching the legal aid office, limited linguistic diversity among legal aid lawyers, higher opportunity cost of opting for legal aid and subpar quality of service.