Post-acute COVID-19 syndrome is frequently observed in workers and has a substantial impact on work ability. We conducted a health promotion program to identify cases of post-COVID syndrome, analyze the distribution of symptoms and their association with work ability. Of the 1422 workers who underwent routine medical examination in 2021, 1378 agreed to participate. Among the latter, 164 had contracted SARS-CoV-2 and 115 (70% of those who were infected) had persistent symptoms. A cluster analysis showed that most of the post-COVID syndrome cases were characterized by sensory disturbances (anosmia and dysgeusia) and fatigue (weakness, fatigability, tiredness). In one-fifth of these cases, additional symptoms included dyspnea, tachycardia, headache, sleep disturbances, anxiety, and muscle aches. Workers with post-COVID were found to have poorer quality sleep, increased fatigue, anxiety, depression, and decreased work ability compared with workers whose symptoms had rapidly disappeared. It is important for the occupational physician to diagnose post-COVID syndrome in the workplace since this condition may require a temporary reduction in work tasks and supportive treatment.