To determine the effectiveness of a pragmatic health promotion program to improve the metabolic disorders in older workers in Taiwan, we conducted a 24-week quasi-experiment in three worksites in southern Taiwan in 2010. Among 1,245 workers, 108 met the inclusion criteria (full-time workers aged over 50 years) and agreed to participate in the study. They were assigned to either the intervention (n = 58) or the reference group (n = 50) according to their availability to participate in health-promoting activities. The intervention group received training in behavioral modifications to improve diet, time-use, stress management and physical activity. Motivational lectures, group activities, and team competitions were used to improve participants' knowledge and skills in managing own health. Subjects in the reference group received no intervention. Lifestyle, anthropometric and biochemical indicators were measured at baseline and end-point. Mixed effects linear models were used to determine the intervention effects. The intervention significantly lowered body weight (intervention vs. reference = -1.22 vs. -0.30kg, p = 0.026), BMI (-0.46 vs. -0.02kg/m2, p = 0.006), and waist circumference (-2.68 vs. +0.79cm, p <0.001), but had no effect on biochemical parameters. These findings suggest the workplace-based health promotion can be effective and useful in reducing the risk of metabolic disorders in older workers in Taiwan.