Adolescents and young adults (AYAs) with life-threatening illnesses need support to discuss and voice their end-of-life choices. Voicing My CHOiCES (VMC) is a research-informed American advanced care planning guide designed to help facilitate these difficult discussions. This multi-perspective study aimed to evaluate its appropriateness, acceptability, and clinical considerations for Australian AYAs with cancer. Forty-three participants including AYAs who were either undergoing or recently completed cancer treatment, their parents, and multidisciplinary health professionals assessed the acceptability of each VMC section quantitatively (appropriateness-yes/no, helpfulness and whether content caused stress-1 = not at all, to 5 = very) and qualitatively (sources of stress). AYAs also assessed the benefit and burden of completing several sections of the document, to inform clinical considerations. We conducted a mixed-methods analysis to obtain descriptive statistics and to identify prominent themes. In terms of acceptability, almost all participants (96%) rated VMC as appropriate overall. Perceived helpfulness to their situation (to themselves/their child/their patients), to others, and stressfulness were rated, on average, as 4.1, 4.0, and 2.7/5, respectively. Stress was attributed to individual and personal factors, as well as interpersonal worries. All sections were considered more beneficial than burdensome, except for the Spiritual Thoughts section (Section 6). While VMC is an acceptable advance care planning guide for AYAs with cancer, changes to the guide were suggested for the Australian context. Health professionals implementing VMC will need to address and mitigate anticipated sources of stress identified here. Future research evaluating the impact of a new culturally adapted Australian VMC guide is an important next step. Finally, the clinical implications of the present study are suggested.