Objective: The current study investigated the experiences, wellbeing impacts, and coping strategies of frontline workers who participated in “Hotels for Heroes”, an Australian voluntary hotel quarantine program during the COVID-19 pandemic. The program was open to those who were COVID-19 positive or exposed to COVID-19 as part of their profession. Methods: Frontline workers who had stayed in voluntary quarantine between April 2020 and March 2021 were invited to participate in a voluntary, anonymous, cross-sectional online survey including both quantitative and qualitative responses. Complete responses were collected from 106 participants, which included data on sociodemographic and occupational characteristics, experiences of the Hotels for Heroes program, and validated mental health measures. Results: Mental health problems were prevalent amongst frontline workers (e.g., moderate anxiety symptoms, severe depression symptoms, and greater than usual impact of fatigue). For some, quarantine appeared to be helpful for anxiety and burnout, but quarantine also appeared to impact anxiety, depression, and PTSD negatively, and longer stays in quarantine were associated with significantly higher coronavirus anxiety and fatigue impacts. The most widely received support in quarantine was from designated program staff; however, this was reportedly accessed by less than half of the participants. Conclusions: The current study points to specific aspects of mental health care that can be applied to participants of similar voluntary quarantine programs in the future. It seems necessary to screen for psychological needs at various stages of quarantine, and to allocate appropriate care and improve its accessibility, as many participants did not utilise the routine support offered. Support should especially target disease-related anxiety, symptoms of depression and trauma, and the impacts of fatigue. Future research is needed to clarify specific phases of need throughout quarantine programs, and the barriers for participants receiving mental health supports in these contexts.