Celiac disease (CD) is an autoimmune gastrointestinal disorder that requires a strict lifelong gluten-free diet (GFD). Gluten-free (GF) foods are more expensive and less readily accessible than gluten-containing foods, contributing to an increased risk for food insecurity (FI). The study aimed to determine associations between GF-FI, sociodemographic risk factors and child dietary adherence and diet quality (DQ). A 26-item, cross-country online survey was administered through social media to parents of children with CD on the GFD. The survey elicited household and CD child sociodemographic and clinical characteristics (e.g., duration of CD), measures of household FI, child DQ and GFD adherence, and parents' concerns related to GF food. Household GF-FI was evaluated using the validated Hunger Vital Sign™ and the US Department of Agriculture Six-Item Short Form Household Food Security Survey Module. GF-FI occurred in 47% of households with children with CD with >30% reporting low to very low food security. Sociodemographic risk factors identified included lower income, renters, rural residency, single-parental households, and having children with additional dietary restrictions (p < 0.001). Regardless of FI status, a majority of households reported experiencing significantly higher GF food expenditure. GF-FI was associated with reduced adherence to the GFD, increased consumption of processed GF food, and lower intakes of fresh fruits and vegetables and GF grains among children with CD (p < 0.05). GF-FI is prevalent in this multiethnic cohort of households with CD children and is associated with worsening DQ and GFD adherence. Policy interventions are urgently needed to address GF-FI.