Children diagnosed with attention deficit hyperactivity disorder (ADHD) require early intervention and sustained treatment. This study used a game-based digital treatment planning NeuroWorld DTx to analyze the impact on attention and cognitive function in children with ADHD. Thirty children diagnosed with ADHD were recruited and subjected to a four-week NeuroWorld DTx digital treatment. To assess the impact of the digital therapeutic therapy on children’s attention, we used the comprehension attention test (CAT) and Korean ADHD Rating Scale (K-ARS). Clinical global impression (CGI) and the Korean-child behavior checklist (K-CBCL 6–18) were used to examine the degree of improvement in ADHD. After four weeks, significant differences in the sensitivity and response style indices were noted, as compared with the baseline in the CAT test; in the case of K-ARS and CGI, a moderate decrease in ADHD was confirmed. The study achieved better results for the “total behavior problems” belonging to the K-CBCL assessment. Game-based digital therapy intervention can be a treatment method that elicits interest and satisfaction in children with ADHD and can be used as an adjunct to drug therapy to improve the quality of life and strengthen attention in children with symptoms of ADHD.