This study aims to gain novel insight into the effect of code-switching experience on the mechanisms that underlie the bilingual advantage in cognitive control. We compared the performances of early and late Japanese-English bilinguals on the AX-CPT Tasks. We found with the late bilinguals, the more frequently they switched languages in their L1 environment, the better they performed in the proactive control tasks. In contrast, with the early bilinguals, the frequency of code-switching did not modulate their dual mechanism of cognitive control any better. These findings verify the role of switching frequency in the development of cognitive control and suggest a better understanding of the nature of mechanisms regulating early and late bilinguals’ brains.