Background: Evidence suggests that there is a gap in advance care planning (ACP) completion between vulnerable and disadvantaged populations compared with the general population. This review seeks to identify tools, guidelines or frameworks that have been used to support ACP interventions with vulnerable and disadvantaged adult populations as well as their experiences and outcomes with them. The findings will inform practice in ACP programmes. Methods: A systematic search of six databases from 1 January 2010 to 30 March 2022 was conducted to identify original peer-reviewed research that used ACP interventions via tools, guidelines or frameworks with vulnerable and disadvantaged adult populations and reported qualitative findings. A narrative synthesis was conducted. Results: Eighteen studies met the inclusion criteria. Relatives, caregivers or substitute decision-makers were included in eight studies. Settings: hospital outpatient clinics (N=7), community settings (N=7), nursing homes (N=2), prison (N=1) and hospital (N=1). A variety of ACP tools, guidelines or frameworks were identified; however, the facilitator's skills and approach in delivering the intervention appeared to be as important as the intervention itself. Participants indicated mixed experiences, some positive, some negative and four themes emerged: uncertainty, trust, culture and decision-making behaviour. The most common descriptors relating to these themes were prognosis uncertainty, poor end-of-life communication and the importance of building trust. Conclusion: The findings indicate that ACP communication could be improved. ACP conversations should incorporate a holistic and personalised approach to optimise efficacy. Facilitators should be equipped with the necessary skills, tools and information needed to assist ACP decision-making.