Objectives The present study aimed at combining previous separate research findings having shown that executive functions (EF) contribute to a large range of emotional and behavioral problems among youths with and without neurodevelopmental disorders such as dyslexia and ADHD. Within a unifying framework, it investigated the mediational roles of ADHD symptoms and emotion regulation (ER) difficulties in the association between various EF and internalizing symptoms. Methods The sample included 82 adolescents with ADHD, dyslexia, comorbid ADHD/dyslexia, and typically developing adolescents, thus showing varying EF deficits. Whereas EF (attentional control, inhibition, shifting, working memory) were assessed in behavioral tasks, parents reported on ADHD symptoms, and ER and internalizing (anxiety, depression) symptoms were assessed via self-reports. Results In two-path mediation analyses, ADHD symptoms and ER problems mediated the association between working memory and anxiety (via inattention and ER, a(1)d(21)b(2) = - .27, 95% CI [- .58, - .04]; via hyperactivity and ER, a(1)d(21)b(2) = - .19, 95% CI [- .42, - .02]) and depression symptoms (via inattention and ER, a(1)d(21)b(2) = - .20, 95% CI [- .54, - .03]; via hyperactivity and ER, a(1)d(21)b(2) = - .24, 95% CI [- .48, - .03]). Hyperactivity and ER, but not inattention and ER, mediated the association between inhibition and internalizing symptoms (predicting anxiety, a(1)d(21)b(2) = .003, 95% CI [.0001, .009]; predicting depression, a(1)d(21)b(2) = .004, 95% CI [.002, .009]) as well as between attentional control and internalizing symptoms (predicting anxiety, a(1)d(21)b(2) = .01, 95% CI [.001, .03]; predicting depression, a(1)d(21)b(2) = .01, 95% CI [.004, .03]). Conclusions These results offer an insight into how ADHD symptoms and ER problems mediate the association between EF components and internalizing symptoms, with potential implications for prevention and intervention measures.