The present study aimed to investigate potential associations between mindfulness and two prominent “cognitive” personality questionnaires (attentional control scale (ACS) and the cognitive failures questionnaire (CFQ)). Moreover, all participants (N = 537, n = 384 females; mean age = 23.30; SD = 5.15) provided buccal swaps for genotyping a classic polymorphism (COMT Val158Met/rs4680) known to influence dopaminergic catabolism on the biochemical level, as well as cognitive functions on a psychological level. Our results show that mindfulness is robustly linked to the ACS (positively) and the CFQ (negatively). The Met/Met genotype of the COMT polymorphism was associated with lower mindfulness (F(1, 535) = 8.27, p = .004; allele level) and higher everyday cognitive failure (F(1, 535) = 9.23, p = .003; allele level). But no significant effects of COMT Val158Met genotype could be observed for attentional control. The present findings provide evidence that the genetic COMT make up of a person could in parts explain self-reported skills in mindfulness and everyday cognitive failure. Based on the direction of the results, possible underlying factors are discussed. As such, COMT effects on an affective facet, which underlies mindfulness and everyday cognitive failures but not attentional control, may drive the effects. As still only a small part of the variance in the constructs is explained by the COMT polymorphism, potentially more genetic polymorphisms should additionally be taken into account in future studies to explain more variance. Genes involved in the dopaminergic neurotransmission seem to be an optimal starting point.