Background/Objectives: Research indicates that children with autism spectrum disorder (ASD) exhibit a deficiency in skills and initiative when it comes to adhering to daily oral hygiene routines. This, in turn, increases the likelihood of oral pathologies, thereby placing a significant emotional strain on their parents. In addition to the typical stress they already experience, parents of children with ASD are also burdened with pediatric oral health issues. However, a review of the literature reveals a lack of studies measuring stress in parents of children whose oral health affects their autistic condition. This research aimed to design and to validate a stress scale for parents of autistic children with poor oral hygiene. Methods: The study used an exploratory, non-experimental design to validate and determine the reliability of the scale. Scale reliability was assessed through a cross-sectional pilot test to evaluate internal scale consistency, with a focus on item similarity. We used Aiken’s V to estimate the validity of the scale, and Cronbach’s α for calculating scale reliability. Calculations, estimations, and statistical analysis were conducted using SPSS. Results: Expert validation, a pilot test, and a cross-sectional, non-experimental design established the reliability of the scale. Conclusions: We conclude that the 20-item scale exhibits validity (0.95) and reliability (0.965), ensuring its applicability in future research.