Telomere integrity is critical for chromosomal stability. Evidence is rapidly growing that impaired telomere integrity may explain the higher risk of some diseases among specific occupations. This review aimed to assess the impact of occupational toxicants exposure on telomere length (TL) and to identify each toxicant's mechanism of action based on an integrative review of available evidence. A literature search was carried out using a set of keywords in different databases. Searches were limited to English publications from 2009 to 2019. Only studies that were using blood samples for TL measurements were included. Finally, 22 studies with a total of 5674 participants, were included. These studies included factory workers from various industries, farmers, coke-oven workers, hairdressers, traffic officers, and drivers. The toxicants were grouped into four categories, including persistent organic pollutants (7 articles), aromatic amines (9 articles), heavy metals (3 articles), and fine particulate matter (PM2.5) (3 articles). Different effects of the same toxicant in TL were observed in various occupations. Factors such as biological characteristics of exposed individuals (especially gene variations and age), diet, lifestyle, dose, and duration of exposure might have modulatory effects on mechanisms and extent of influences of toxicants on TL. Further possible modes of actions affecting the TL are oxidative stress, telomerase expression, systemic inflammation, epigenetic modification, and genotoxicity. In conclusion, various toxicants affect TL differently, but the effect may be moderated by improving the workers’ lifestyle. The involvement of different interrelated pathways may explain the differences in TL alterations.