Inhibitory control (IC) – one of the most critical functions underlying a child's ability to self‐regulate – develops significantly throughout the kindergarten years. Experiencing negative emotions imposes challenges on executive functioning and may specifically affect IC. In this study, we examined kindergartners' IC and its related brain activity during a negative emotional situation: 58 children (aged 5.5–6.5 years) performed an emotion‐induction Go/NoGo task. During this task, we recorded children's performance and brain activity, focusing on the fronto‐central N2 component in the event‐related potential (ERP) and the power of its underlying theta frequency. Compared to Go trials, inhibition of NoGo trials was associated with larger N2 amplitudes and theta power. The negative emotional experience resulted in better IC performance and, at the brain level, in larger theta power. Source localization of this effect showed that the brain activity related to IC during the negative emotional experience was principally generated in the posterior frontal regions. Furthermore, the band power measure was found to be a more sensitive index for children's inhibitory processes than N2 amplitudes. This is the first study to focus on kindergartners' IC while manipulating their emotional experience to induce negative emotions. Our findings suggest that a kindergartner's experience of negative emotion can result in improved IC and increases in associated aspects of brain activity. Our results also suggest the utility of time‐frequency analyses in the study of brain processes associated with response inhibition in young children. Inhibitory control (IC) ‐ one of the most critical functions underlying a child's ability to self‐regulate ‐ develops significantly throughout the kindergarten years. Experiencing negative emotions imposes challenges on executive functioning and may specifically affect IC. In this study, we examined kindergartners' IC and its related brain activity during a negative emotional situation. We found that theta power within the N2 window was increased in NoGo trials of the negative emotional block (B), compared to the non‐negative emotional blocks (A and C). This increase reflects the recruitment of emotional and attentional resources needed when children were asked to cope with their negative emotions and exert inhibitory control under this challenging condition.