Swallowing dysfunction, or dysphagia, is a critical concern among older residents in long-term care facilities because it contributes to malnutrition and increased frailty. Oral hypofunction, characterized by a decline in oral function, is recognized as a precursor to oral dysfunction. This study investigated the prevalence of oral hypofunction and assessed the effectiveness of oral health education and oral exercises in improving oral function. A total of 295 participants from seven long-term care facilities in Taiwan were recruited for this study, and they underwent comprehensive assessments. The key domains assessed were oral health, swallowing function, nutritional status, and frailty. The interventions included oral hygiene education and tongue-lip exercises, which were administered over a 6-month period. Outcomes such as swallowing function, oral health, tongue pressure, tongue-lip motor function, nutritional status, grip strength, and cheek bulging were measured at three time points. The prevalence of oral hypofunction in the participants was 58.3%. The intervention led to significant improvements in swallowing function 6 months later and in oral hygiene and tongue-lip motor function 3 months later in the participants with oral hypofunction. Additionally, in the oral hypofunction group, nutritional status and cheek bulging function were notably improved after 6 months. Oral hygiene education and oral exercises were demonstrated to effectively enhance swallowing function, oral hygiene, and tongue-lip motor function in older residents with oral hypofunction, thereby improving their nutritional status. Early identification and intervention are crucial for improving oral function in long-term care settings.