Complaints of cognitive functions (CCFs), defined as subjective cognitive dysfunction, affect social function; additionally, for workers, this condition is an important factor in presenteeism and mediates the effect of depressive symptoms on presenteeism. This study aimed to investigate whether CCFs mediate the relationships among insomnia, state anxiety (SA), and presenteeism. Participants were 471 Japanese adult workers evaluated using the Athens Insomnia Scale, State-Trait Anxiety Inventory (Form Y), Cognitive Complaints in Bipolar Disorder Rating Assessment, and Work Limitations Questionnaire 8 to assess insomnia, SA, CCFs, and presenteeism, respectively. Path analysis was used to evaluate the correlations between variables. CCFs significantly mediated the associations among insomnia, SA, and presenteeism. To address the presenteeism associated with insomnia and SA, it may be useful to assess the mediating roles of CCFs.