Background/Objectives: The dental and oral health status of adolescents in Indonesia, especially in Gorontalo City, remains concerning with a high caries prevalence. Conventional education efforts are less effective in forming sustainable healthy behaviors. This study aims to analyze the effectiveness of the application-based Motivational Interviewing (MI) implementation to improve the dental and oral health status of adolescents. Methods: The study used a quasi-experimental one-group pre-test post-test design involving 100 adolescents aged 15–18 years and 30 health cadres. Subjects were divided into an application-based MI intervention group (n=50) and a control group (n=50). The intervention was given for three months, with regular measurements of knowledge, toothbrushing behavior, and oral hygiene status (OHIS). Statistical analysis used the Wilcoxon Signed Ranks Test and Mann Whitney test. Results: There was a significant increase in knowledge scores, toothbrushing behavior, and OHIS status in the combined MI intervention group (P-value<0.001) compared to the control group. The integration of face-to-face and digital methods proved more effective in forming sustainable healthy behaviors. Conclusions: Hybrid MI combining mobile application support with face-to-face counseling is significantly more effective in improving oral hygiene status among adolescents compared to conventional education. This model is recommended as an adaptive promotive–preventive strategy for adolescent oral health programs.