Background: Oral hygiene is often neglected in clients receiving long-term care, suggesting that long-term care workers require formal oral hygiene education. Thus, the aim of this study was to investigate the effects of oral hygiene education on long-term care workers. Methods: This study utilized a mixed methods design. Eighty long-term care workers were recruited for participation in the oral hygiene education program, which employed three teaching methods: narration with multimedia presentation, demonstration, and teach-back. The effect of the education program on the participants’ level of oral hygiene knowledge, attitudes, and skills was measured using a structured questionnaire that was administered both pre- and post-delivery of the education program. Three months later, all participants submitted a self-report of their oral hygiene skills, and six participants completed a telephone interview. Quantitative data were analyzed using paired t-tests, and qualitative data were manually analyzed and coded. Results: Scores of oral hygiene knowledge (p < 0.001), attitudes (p = 0.001), and oral cleaning daily frequency for clients (p < 0.001), were significantly higher three months after undertaking the educational program. Conclusions: This preliminary study suggests that oral hygiene education may be effective in improving oral hygiene knowledge, attitudes, and skills among long-term care staff.