Executive functions (EFs) play a crucial role in academic performance. In the present study, we aimed to improve EFs through a group-based cognitive training. Thirty-three typically developing children (age mean: 58.80 ± 7.04 months) were recruited in a random clinical trial design in two intervention (n = 18) and active control (n = 15) groups. Emoji selection, shifting attention, day/night Stroop, Corsi block tapping tasks, and behavioral rating inventory of executive function (BRIEF) were used for assessment in three baseline, post-intervention, and 3-month follow-up sessions. The intervention group received Class-based Cognitive Remediation (COREN) and the active control group participated in a storytelling class, both in 12 sessions. The result suggests improvement in sustained attention, cognitive flexibility, inhibitory control, and working memory in intervention group. The rating scales showed improvement in executive functioning in the intervention group based on parental rating. Group-based cognitive training is beneficial to improve EFs in kindergarten.