The high prevalence of overweight and obesity is a major contributor to the global burden of disease, and create an economic burden for nations, including both direct and indirect costs. Although the Kingdom of Saudi Arabia is rapidly industrializing and the economy is now less dependent on oil, oil industry is still the main contributor to the Saudi labor force (41%). However, the productivity growth lags behind many developing countries. No studies have been conducted to explore the factors that can be associated with the lower productivity in this population of Saudi Arabia. This study aimed to estimate the prevalence of overweight/obesity and examine the association between overweight/obesity and lifestyle habits among employees of petrochemical manufacturing companies in the Kingdom of Saudi Arabia. A total of 1000 employees were surveyed. Chi-square test and logistic regression were used to predict odds ratios for obesity. About 47% of the sample was normal weight, while 28.5% was overweight and 21.2% was obese. Four factors were found to be predictive of obesity: feelings about weight, age, marital status, and childhood region. More than 52% of employees reported being happy with their weight. Those unhappy with their weight had more than six times greater odds of obesity as compared to those happy with their weight. Married employees were about twice as likely as unmarried to be obese. The findings of high prevalence of overweight and obesity among employees of petrochemical manufacturing suggest that more efforts are needed to promote healthy behaviors among employees. Workplace wellness programs and educational campaigns are recommended to encourage healthy lifestyle habits at both the workplace and in the community.