Background: Poor intelligibility is common in young children with developmental language disorders (DLDs). Relatedly, children with DLD and poor intelligibility, like children with DLD solely, have often also difficulties in other aspects of language abilities: such as making grammatical and cohesive sentences and telling narratives with an adequate plot structure. However, relatively few studies examined the relation between speech production, narrative cohesion, and narrative coherence in one and the same design. Aim: This research was conducted to investigate the relation between speech production, narrative cohesion, and narrative coherence in children with DLDs and poor intelligibility. Methods and Procedures: One hundred and forty-nine 4-to-6-year-old children with DLD and poor intelligibility who were referred for special treatment to improve their speech production, were included in this study. Speech and language assessments were conducted at the start of the treatment, and the results of these assessments were used in the current study. For speech production, spontaneous language was analysed to derive measures for the production of consonants, vowels, and word structure. Additionally, a measure of nonword repetition was used. For narrative production, the Frog Story Test was used, resulting in a measure of narrative cohesion (sentence production) and a measure of narrative coherence (plot structure). Effects of hearing and chronological age on speech and language production were controlled for in the analyses. Outcomes and Results: Mediation analysis demonstrated that there was no direct effect of speech production on narrative coherence but the indirect effect was significant. The relation between speech production and narrative coherence was fully mediated by narrative cohesion, also when controlling for age and hearing capacity. Significant effects were also found for the relation between speech production and narrative cohesion and between narrative cohesion and narrative coherence. Conclusions and Implications: This study confirms that the relation between speech production and narrative coherence in children with DLD and poor intelligibility is fully mediated by children's narrative cohesion performance. For clinical practice, these results show the importance of fostering both speech and language production capacities in strengthening the narrative performance of these children.