The COVID-19 pandemic and imposed restrictions had negative consequences on overall health among many populations. This study aimed to investigate the influence of the pandemic on eating disorders (ED) and mental health (MH) of individuals with confirmed ED diagnoses. A survey consisting of questions related to (1) diagnosis of COVID-19, (2) changes in ED symptoms and onset of new symptoms, (3) psychological and MH aspects regarding to the pandemic, (4) lifestyle changes, and (5) social media (SM) usage was distributed between April–June 2021. One hundred and ninety-eight individuals met all of the inclusion criteria (n_females = 195, 98.48%; n_{other gender} = 3, 1.52%). Of the participants, 78.79% reported worsening of their ED symptoms, 42.93% of them noticed an onset of new ED symptoms, and 57.58% believed that the pandemic had a negative impact on their ED treatment. Negative changes due to the pandemic on MH were reported by 88.89%. Of the participants, 91.92% increased their time spent on SM and 54.04% of them declared that it had a negative impact on their MH. Medical professionals should consider results while providing comprehensive psychological care, which can be crucial information in the application of the appropriate treatment strategy.