Background/Objectives: Post-stroke dysphagia (PSD) is a common complication following cerebrovascular events, and many affected patients also present with pre-existing dementia or post-stroke cognitive impairment (PSCI). PSD primarily affects the oropharyngeal phase of swallowing, whereas cognitive impairment often compromises the oral phase. This overlap complicates diagnosis and highlights the importance of accurate assessment to guide appropriate treatment strategies. Repetitive transcranial magnetic stimulation (rTMS) has emerged as a promising therapeutic intervention for both cognitive impairment and dysphagia. Methods: In this study, we report a case of a patient with pre-existing dementia who experienced an ischemic stroke, resulting in PSD and PSCI. Videofluoroscopic swallowing study (VFSS) revealed oral-phase-predominant dysphagia. rTMS targeting the dorsolateral prefrontal cortex (DLPFC) was administered with the aim of enhancing cognitive function. Results: Following two cycles of rTMS in combination with ongoing swallowing therapy, the patient demonstrated notable improvement in both cognitive and swallowing function. Conclusions: Although limited by a single-case design and the possibility of spontaneous recovery, this case demonstrates that rTMS targeting the DLPFC combined with swallowing therapy may be a potential intervention for managing concurrent post-stroke dysphagia and cognitive impairment.