Vitamin D comes in two forms: ergocalciferol (D2) and cholecalciferol (D3). This study aimed to assess mothers’ knowledge, attitudes, and practices toward vitamin D deficiency among children. We collected data using a self-administered online questionnaire to gather information about the characteristics, knowledge, attitudes, and reported practices of 800 Saudi Arabian mothers regarding vitamin D deficiency. The mean age of participants was 31.2±4.76, and 8% had a university education. When it came to household income, the majority (90.1%) reported that they had enough money. Participants who attended training courses, employed mothers, total practice, and total attitude had a significant favorable effect on knowledge, with a p-value of less than 0.01. Employed mothers, training course attendees, total practice, and overall attitude had a significant favorable effect on mothers’ practice, with a p-value of less than 0.01**. More than half of the mothers who participated in the study had an inadequate level of understanding. Less than two-thirds of those surveyed noted the deficient practice. Two-thirds of the moms who participated in the study had a negative attitude toward vitamin D deficiency. There was a strong positive correlation between total knowledge, total attitude, and total practice-related vitamin D deficiency.