Existing cross-cultural findings related to school-aged children's executive function (EF) from studies using computerized tasks highlight both an East-West contrast (East > West) and potential methodological confounds (e.g., contrasting levels of computer fluency). Capitalizing on two recent data sets, this multisite study of 1,311 children living in mainland China (n = 453; Mage = 11.89 years, SD = 0.87), Hong Kong (n = 371; Mage = 12.21 years, SD = 0.99), and the United Kingdom (n = 487; Mage = 11.91 years, SD = 0.93) tested measurement invariance of a computerized EF-task battery prior to investigating cultural contrasts in mean levels of EF efficiency scores. Our models established partial scalar invariance across sites. Latent factor means were substantially lower for British children than for their counterparts from either mainland China or Hong Kong, with a significant but smaller contrast between the latter two groups. Within the Chinese sample, self-reported computer use was unrelated to variation in children's performance on online tests of EF, indicating that peripheral effects of task modality are unlikely to explain the between-culture differences in EF task performance.