Background: The emergence of acute-onset functional neurological symptoms, the focus of this study, is one of three stress responses related to immunisation. This case–control study documents the experience of 61 young people with past or current functional neurological disorder (FND) in relation to the COVID-19 vaccination program in Australia. Methods: Information about the young person’s/parent’s choice and response pertaining to COVID-19 vaccination was collected as part of routine clinical care or FND research program follow-up. Results: 61 young people treated for FND (47 females, mean age = 16.22 years) and 46 healthy controls (34 females, mean age = 16.37 years) were included in the study. Vaccination rates were high: 58/61 (95.1%) in the FND group and 45/46 (97.8%) in the control group. In the FND group, 2 young people (2/61, 3.3%) presented with new-onset FND following COVID-19 vaccination; two young people with resolved FND reported an FND relapse (2/36, 5.56%); and two young people with unresolved FND (2/20, 10.0%) reported an FND exacerbation. In the control group no FND symptoms were reported. Conclusions: Acute-onset FND symptoms following COVID-19 vaccination are uncommon in the general population. In young people prone to FND, COVID-19 vaccination can sometimes trigger new-onset FND, FND relapse, or FND exacerbation.