Objectives: Our previously published study showed that a workplace nutrition intervention program with personalized goal setting and smartphone-based nutrition counseling improved dietary habits and physical activity in city bus drivers who were overweight/obese. This study explored the facilitators and barriers that participants faced in achieving their dietary and physical activity goals six months after the intervention. Methods: The study included bus drivers and dietitians who participated in the intervention program. Three focus group interviews were conducted with 10 bus drivers (divided by two groups based on their achievement of set goals) and five dietitians who had provided nutrition counseling. Results: Willpower was the most important intrapersonal facilitator for drivers to achieve their goals. Other factors that promoted behavioral changes were nutrition counseling by dietitians, trackable physical activity using smartwatches, and setting of practical and achievable goals. Meanwhile, the most important barriers identified were occupational factors such as long driving hours, short breaks, and shift work. Other barriers were environmental factors such as availability of snackable food, accessibility to convenience stores, and cold weather. Family and colleagues were perceived as both facilitators and barriers. In addition, dietitians identified a lack of knowledge about healthy diet as one of the barriers. Conclusions Our results suggested that the workplace environment should be improved and that nutrition intervention programs at the workplace could encourage bus drivers to practice healthy eating habits. The facilitators and barriers identified in this study should be considered when planning a nutrition intervention program for bus drivers.