This study aimed to examine the association between working hours and anxiety of a working population in Hong Kong. We used a cross sectional data from a population-based household survey of Hong Kong Chinese adults. Key measures included employment status, skill level, working hours, length of stay at current job and anxiety level. Symptoms of anxiety were assessed using the Depression Anxiety Stress Scale (DASS-21). The data were analysed using logistic regression. Chinese adults who had long working hours (≥ 72h per week) had higher odds of developing symptoms of anxiety than those who worked for ≤ 36h per week (odds ratio [OR] 5.94, 95% confidence interval [CI]: 1.82‒19.41). Compared with short period (< 1year), long period of stay at current job (≥ 5years) was found as a protective factor from anxiety (OR 0.38, 95% CI: 0.20‒0.73). We found that a working period of 72h per week was a significant threshold to cause anxiety to workers. Stable job arrangement was a protective factor to workers from anxiety. Implementation of labour market regulations, such as standard working hour policy and stable job arrangement, was also significant to mitigate risk of anxiety for working people in Hong Kong.