Background: In Austria, almost every second child has caries. The consequences of untreated carious lesions are infections, pain, and limitations in everyday life. The aim of this study was to evaluate the influence of silver diamine fluoride (SDF) treatment on the oral health-related quality of life (OHRQoL) of uncooperative children aged 0–5 years using the German version of the Early Childhood Oral Health Impact Scale (ECOHIS-G). Methods: This prospective study was conducted at the Department of Paediatric Dentistry at the Medical University of Vienna. Preschool children with behavioral problems and carious lesions that required SDF application were included. The ECOHIS-G questionnaire was given to the caregiver before (T0) and three months (T1) after treatment. Using descriptive analysis and the Wilcoxon Signed-Rank test, changes in the ECOHIS scores were evaluated and tested for significance. Results: A total of 30 children aged 0–5 years were enrolled and received SDF treatment. At baseline, the total ECOHIS score was 21.4 (±8.5). Three months after therapy, a significant improvement was achieved (16.3 [±5.6], p < 0.05). Significantly better scores were observed in six subdomains, especially in “child function” (3.9 [±2.0]) and “child symptoms” (2.0 [±1.3]) (p < 0.05). Conclusions: Treatment of carious lesions with SDF in the primary dentition resulted in an improvement in the OHRqoL of children with behavioral problems.