Increasing evidence supports the existence of time-related impairments in school-aged children and adults with Attention-Deficit/Hyperactivity Disorder (ADHD), but this deficit has not yet been investigated in preschoolers with ADHD. The aim of the current study was to determine the extent to which time-related impairments can be identified within the context of parent–child interactions in preschoolers with ADHD. Participants for this study included 29 children with ADHD and 34 typically developing (TD) children (63.5% male; Mage = 4.77, SD = 0.65; 82.5% Hispanic/Latinx), and their parents. A ten-minute play session was video-recorded for each parent-child dyad. The verbal interactions were transcribed and coded for words/expressions related to the categories of time (e.g., “later”, “tomorrow”), as well as mathematics (e.g., “two more”, “some”), and space (e.g., “here/there”, “behind”). The proportion of tokens (total number of terms) and types (different terms) of each category was calculated in relation to the total verbal production for each individual (i.e., parents and children separately), and differences between groups were analyzed. Results indicated that compared to TD children, children with ADHD showed a poorer vocabulary of time-related words (d = 0.63), whereas similar rates between groups were found for the math- and space-related words. Correlation analyses revealed significant associations between the types of time-related words used by children, and problems with attention and executive functioning. These results offer some evidence for not only the presence of time-related deficits in preschoolers with ADHD, but also the association between time-related deficits and impairments in cognitive functioning.