This study investigated the complex relationship between false-belief (FB) understanding, structural language and pragmatic communication in typically developing children. A total of 78 Finnish children, aged from 4 to 6 years, including an equal number of boys and girls, participated in this study. In the first instance, the study explored the relationship between children’s structural language skills and their understanding in FB tasks. The children’s structural language was evaluated using the Token Test for Children, German’s Test of Word Finding and the structural language scales (Speech, Syntax, Semantics and Coherence) of the Children’s Communication Checklist (CCC-2). Subsequently, the study examined the relationship between FB understanding and pragmatic communication skills, as measured by the pragmatic communication scales of the CCC-2 (Inappropriate Initiation, Stereotyped Language, Use of Context and Non-verbal Communication). In addition, the study investigated the effect of sex on these skills. A significant effect was found between the ability to understand verbal instructions and FB reasoning. However, no significant effect was found for naming and word retrieval abilities, nor for linguistic abilities as assessed by the CCC-2’s structural linguistic scales. Furthermore, children who demonstrated higher skills in understanding the mental states of others also exhibited better pragmatic communication skills using the CCC-2’s pragmatic scales. Although girls outperformed boys in the FB task, sex did not significantly predict pragmatic communication skills. The result suggests interrelatedness of language comprehension and FB understanding, as well as between FB and pragmatic communication abilities in typically developing preschool children.