Molar incisor hypomineralisation (MIH) is a dental enamel pathology responsible for unfavorable functional and aesthetic implications. The objective of this study is to assess the prevalence, dental anxiety, and quality of life related to oral health in children with MIH. In 14 schools in Brussels, Belgium, 290 children aged 8 to 9.5 answered Children’s Fear Survey Schedule-Dental Subscale (CFSS-DS) and Child-Oral Impact on Daily Performance (C-OIDP) questionnaires to assess dental anxiety and quality of life related to oral health (OHRQoL). Oral examinations allowed us to detect MIH according to standardized criteria. The MIH prevalence was 18.6%. The Decayed, Missing and Filled Teeth index (DMFT index) of MIH patients was significantly higher than non-MIH patients (p < 0.001), mainly due to more restored teeth. There was no significant association between MIH and dental anxiety or OHRQoL. Caries in the deciduous dentition was significantly associated with impaired quality of life. The MIH prevalence in Brussels is comparable to other European countries. MIH had no significant impact on dental anxiety and OHRQoL in this sample. The dynamic nature of MIH lesions requires early diagnosis and management to limit the evolution of the severity of the lesions and their implications. It is possible that older age groups may present more symptoms, however, this would require a longitudinal study.