Executive functions like working memory, inhibitory control, and cognitive flexibility are a set of neurocognitive processes involved in reasoning, planning, and self-regulatory skills that allow goal-oriented behaviors. Mounting evidence supports the importance of these processes for educational success from early on. Executive functions can be improved by employing computerized activities. However, most of the evidence with gamified tasks comes from controlled studies in laboratory settings, while the efficiency of interventions deployed in real-world circumstances is scarce. Furthermore, the effectiveness of an intervention might be modulated by school socioeconomic status, but the evidence in this regard is still limited. The present study examined the efficiency of a short training program, aimed to stimulate executive functions, deployed in high- and low-socioeconomic school kindergarten classes. One hundred and thirty-six children (M = 5.30, SD = 0.36 years old) participated in a randomized, pre/post, controlled design. Data were analyzed with multilevel analysis. We found that all children that participated in the training group improved their working memory span and performance in a fluid intelligence task. Gains in inhibitory control and cognitive flexibility were observed only in children from low socioeconomic background schools. We also explored far-transfer effects on non-trained skills. We found no evidence of improved performance in a planning task, or classroom behaviors typically associated with executive functions. Our results show that it is possible to promote cognitive development in kindergarteners through video games played within classrooms of diverse sociocultural contexts.