In recent years, there has been increasing interest in understanding how cognitive skills influence second language acquisition. Cognitive control, a set of mental processes that include attention, inhibition, and working memory, has been shown to play a significant role in language learning. This study examines the impact of cognitive control skills on language development among adult Iranian English learners, comparing it both in online and in person settings. Forty adult EFL learners were divided into two groups and underwent a 9-week instructional period, with cognitive control skills assessed using the Attention Network Task (ANT), working memory tasks, and a Raven’s IQ test. Data were analyzed using Pearson correlation, regression, and ANCOVA to determine relationships between variables. The results of the study revealed that while aspects of cognitive control like orienting and altering do not have a significant impact on language development, the more complex, controlling aspect exhibits a positive relationship (F=4.937, p=0.033). This relationship was contingent upon controlling for differences between post-examination and primary examination of ANT results, indicating that controlling attention is a stronger predictor of language outcomes. Furthermore, the study demonstrated that the mode of instruction—online or in-person—has no significant impact on this relationship (F=0.009, p=0.925), suggesting that cognitive control operates independently of teaching mode. The study’s findings suggest that educators and curriculum developers should emphasize activities targeting the controlling component of cognitive control in language learning, as this is linked to better language development. Additionally, since the mode of instruction does not significantly impact this relationship, effective language instruction can be delivered in both online and in-person settings, providing flexibility in course design.