Bimodal bilingualism involves the use of a sign language and a spoken language, and offers a unique opportunity to explore the cognitive effects of growing up bilingual. The aim of this study was to investigate the relationship between bimodal bilingualism and executive function (EF) in hearing children who are native users of a sign language. We studied three groups of children: bimodal bilinguals (users of a sign language and a spoken language), unimodal bilinguals (users of two spoken languages), and monolinguals, performing three cognitive tasks to measure different components of EF: visuospatial working memory (Odd One Out task), cognitive flexibility (Children's Colored Trails Test) and conflict resolution (Simon task). All groups of children obtained similar scores on the Odd One Out task and the Children's Colored Trails Test. Bimodal bilinguals displayed distinct patterns of conflict resolution in comparison to monolingual children: bimodal bilinguals had better overall accuracy and slower overall reaction time in the Simon task. The subsequent analysis did not find a straightforward trade-off between speed and accuracy. These results suggest that bimodal language experience and/or visual-spatial language usage may explain the small bimodal bilingual advantage in the Simon task that we observed in hearing children who are native signers.