The validation of a new questionnaire is essential to improving its credibility in the assessment and collection of evidence. This study aimed to validate a newly developed infant and young child feeding questionnaire for child care providers (IYCF-CCPQ) to measure the knowledge, attitudes, and practices regarding infant and young child feeding among them. A cross-sectional study was conducted with 200 child care providers who were involved in handling children less than two years old in child care centers in the northeastern part of Peninsular Malaysia. The IYCF-CCPQ was self-administered and consists of three domains: Knowledge (104 items), attitude (90 items), and practice (42 items). The dichotomous-scale items in the knowledge domain were analyzed using a two-parameter logistic model of item response theory (2-PL IRT). The Likert-type-scale items in the attitude section were assessed using exploratory factor analysis (EFA). The items in the practice section were assessed descriptively. Internal consistency by marginal reliability was assessed in the knowledge domain, and Cronbach's alpha coefficient was used for the attitude domain. The marginal reliability values were 0.91 and 0.74 for the knowledge domains related to breastfeeding/formula feeding and complementary feeding, respectively, and the Cronbach's alpha values were 0.89 and 0.90 for the attitude domains related to breastfeeding/formula feeding and complementary feeding, respectively. The analysis showed good psychometric properties (discrimination, difficulty index, factor loading, and communalities) and good reliability. The IYCF-CCPQ is valid for use assessing the knowledge, attitudes, and practices among Malaysian child care providers regarding infant and young child feeding.