Background: Metacontrol is the ability to optimize the balance between cognitive persistence and flexibility. Recent research points to aperiodic EEG activity as a neurophysiological marker for metacontrol and its modulations. However, the causal link between metacontrol and aperiodic activity is still unclear. Objective: We provide mechanistic insights into the neurobiological foundations of metacontrol and the means to enhance it. We evaluated the interplay of anodal transcranial direct current stimulation (atDCS) and Methylphenidate (MPH), both of which are known to alter cortical noise, a factor that can be measured by aperiodic exponents derived from EEG data. Methods: We examined the impact of right inferior frontal (midpoint between electrodes FC4 and F8) 20 min offline atDCS at 2-mA and MPH administration, both separately and combined, on aperiodic EEG activity while healthy adult participants (N = 98) performed a Go/NoGo task. We used the FOOOF (fitting oscillations & one over f) algorithm to examine aperiodic activity. Results: We obtained an interaction between atDCS stimulation and MPH administration, indicating that atDCS is effective in reducing aperiodic neural activity (i.e., increased aperiodic exponents) when being combined with MPH administration. Conclusion: Aperiodic neural activity can be modulated through pharmacology-tuned atDCS. atDCS and MPH rely on overlapping neurobiological mechanisms. Metacontrol depending on aperiodic neural activity can be modulated through combined atDCS-MPH stimulation. Hence, atDCS and MPH are suitable tools to achieve an exogenous modulation of metacontrol bias and aperiodic exponents are indices to demonstrate the effectiveness of such tools.