The health status of toddlers with un-repaired congenital heart disease relies on maternal care behaviors. This randomized control trial investigated the effects of a Dependent Care Support Program on maternal care behaviors. Participants were 50 mothers of toddlers with non-cyanotic congenital heart disease waiting for surgery. They were randomly assigned to either the experimental group (n = 25) or the control group (n = 25). The experimental group received the usual care plus the program. The control group received only the usual care. Data were collected by using the Maternal Care Behaviors for Congenital Heart Disease Toddlers Scale and the Incidence of Illness Recording Form. Data were analyzed using descriptive statistics, Chi-square test, Fisher’s exact test, independent t-test, and dependent t-test. Results indicated that the maternal care behaviors in the experimental group at week 6 after program implementation were significantly higher than mothers in the control group and were significantly higher than those before attending the program. The incidence rate of illnesses among children in the experimental group (40%) at week 6 was significantly lower than children in the control group (80%). Nurses may implement the 6-week program to improve maternal care behaviors and their children with congenital heart disease to gain optimum health for surgical treatment as planned. Further study should evaluate the effectiveness of the program in long-term follow-up.