Background: Attention deficit hyperactivity disorder (ADHD) is a condition that causes poor academic performance. If left untreated, it can lead to different comorbidities such as depression, anxiety, and substance abuse. Objectives: This study compared the effects of a computer-based intervention (Captain's Log MindPower Builder) combined with Ritalin to those of Ritalin alone on sustained attention, divided attention, and impulsivity in children with ADHD. Methods: The statistical population included all boys and girls with ADHD aged 7 - 12 years who visited Baqiyatallah Hospital of Tehran in 2021 (N = 103). Purposive sampling was employed to select 30 eligible children as the research sample. They were then randomly assigned to an intervention group (Captain's Log MindPower Builder + Ritalin) and a waitlist control group (Ritalin alone). The computer-based intervention was performed in twelve 60-minute sessions. The data were collected by conducting the Integrated Visual and Auditory Continuous Performance Test. The analysis of covariance (ANCOVA) was then utilized to analyze the research data. SPSS software v26 was used for data analysis. Results: The mean ± SD of sustained attention, divided attention and impulsivity were 78.26 ± 6.90, 80.20 ± 6.01, and 73.70 ± 8.91on the pretest in the intervention group; moreover, it was 88.87 ± 7.19, 90.94 ± 5.45, and 82.41 ± 8.46 on the pretest in the control group. According to the results, the computer-based intervention had significant effects on both sustained attention and divided attention; however, it failed to significantly improve impulsivity (P < 0.001). Additionally, the intervention effects during the 45-day follow-up period only showed stability for sustained attention (P < 0.001). In fact, its effects on divided attention and impulsivity control were not significant. Conclusions: The computer-based intervention enhanced Ritalin's effects in some ways and improved sustained attention. Therefore, education centers for children with ADHD are recommended to adopt this method in order to improve attention in such children. Nevertheless, further studies are needed in this field to gain a better insight into the effectiveness of Captain's Log MindPower Builder.